Next: Introduction, Up: (dir) [Index]
This manual documents CLN, a Class Library for Numbers.
Published by Bruno Haible, <haible@clisp.cons.org>
and
Richard B. Kreckel, <kreckel@ginac.de>
.
Copyright (C) Bruno Haible 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008. Copyright (C) Richard B. Kreckel 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014. Copyright (C) Alexei Sheplyakov 2008, 2010.
Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.
Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.
Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the author.
Next: Installation, Previous: Top, Up: Top [Index]
CLN is a library for computations with all kinds of numbers. It has a rich set of number classes:
The subtypes of the complex numbers among these are exactly the
types of numbers known to the Common Lisp language. Therefore
CLN
can be used for Common Lisp implementations, giving
‘CLN’ another meaning: it becomes an abbreviation of
“Common Lisp Numbers”.
The CLN package implements
+
, 
, *
, /
, sqrt
,
comparisons, …),
and
, or
, not
, …),
CLN is a C++ library. Using C++ as an implementation language provides
+
, 
, *
, =
,
==
, … operators as in C or C++.
CLN is memory efficient:
CLN is speed efficient:
i386
, m68k
, sparc
, mips
, arm
).
CLN aims at being easily integrated into larger software packages:
cln
in
order to avoid name clashes.
Next: Ordinary number types, Previous: Introduction, Up: Top [Index]
This section describes how to install the CLN package on your system.
• Prerequisites:  
• Building the library:  
• Installing the library:  
• Cleaning up: 
Next: Building the library, Previous: Installation, Up: Installation [Index]
• C++ compiler:  
• Make utility:  
• Sed utility: 
Next: Make utility, Up: Prerequisites [Index]
To build CLN, you need a C++ compiler.
GNU g++ 4.0.0
or newer is recommended.
The following C++ features are used: classes, member functions, overloading of functions and operators, constructors and destructors, inline, const, multiple inheritance, templates and namespaces.
The following C++ features are not used:
new
, delete
, virtual inheritance.
CLN relies on semiautomatic ordering of initializations of static and global variables, a feature which I could implement for GNU g++ only. Also, it is not known whether this semiautomatic ordering works on all platforms when a nonGNU assembler is being used.
Next: Sed utility, Previous: C++ compiler, Up: Prerequisites [Index]
To build CLN, you also need to have GNU make
installed.
Previous: Make utility, Up: Prerequisites [Index]
To build CLN on HPUX, you also need to have GNU sed
installed.
This is because the libtool script, which creates the CLN library, relies
on sed
, and the vendor’s sed
utility on these systems is too
limited.
Next: Installing the library, Previous: Prerequisites, Up: Installation [Index]
As with any autoconfiguring GNU software, installation is as easy as this:
$ ./configure $ make $ make check
If on your system, ‘make’ is not GNU make
, you have to use
‘gmake’ instead of ‘make’ above.
The configure
command checks out some features of your system and
C++ compiler and builds the Makefile
s. The make
command
builds the library. This step may take about half an hour on an average
workstation. The make check
runs some test to check that no
important subroutine has been miscompiled.
The configure
command accepts options. To get a summary of them, try
$ ./configure help
Some of the options are explained in detail in the ‘INSTALL.generic’ file.
You can specify the C compiler, the C++ compiler and their options through
the following environment variables when running configure
:
CC
Specifies the C compiler.
CFLAGS
Flags to be given to the C compiler when compiling programs (not when linking).
CXX
Specifies the C++ compiler.
CXXFLAGS
Flags to be given to the C++ compiler when compiling programs (not when linking).
CPPFLAGS
Flags to be given to the C/C++ preprocessor.
LDFLAGS
Flags to be given to the linker.
Examples:
$ CC="gcc" CFLAGS="O" CXX="g++" CXXFLAGS="O" ./configure
$ CC="gcc V 3.2.3" CFLAGS="O2 finlinelimit=1000" \ CXX="g++ V 3.2.3" CXXFLAGS="O2 finlinelimit=1000" \ CPPFLAGS="DNO_ASM" ./configure
$ CC="gcc4.2" CFLAGS="O2" CXX="g++4.2" CXXFLAGS="O2" ./configure
Note that for these environment variables to take effect, you have to set
them (assuming a Bournecompatible shell) on the same line as the
configure
command. If you made the settings in earlier shell
commands, you have to export
the environment variables before
calling configure
. In a csh
shell, you have to use the
‘setenv’ command for setting each of the environment variables.
Currently CLN works only with the GNU g++
compiler, and only in
optimizing mode. So you should specify at least O
in the
CXXFLAGS, or no CXXFLAGS at all. If CXXFLAGS is not set, CLN will be
compiled with O
.
The assembler language kernel can be turned off by specifying
DNO_ASM
in the CPPFLAGS. If make check
reports any
problems, you may try to clean up (see Cleaning up) and configure
and compile again, this time with DNO_ASM
.
If you use g++
3.2.x or earlier, I recommend adding
‘finlinelimit=1000’ to the CXXFLAGS. This is essential for good
code.
If you use g++
from gcc3.0.4 or older on Sparc, add either
‘O’, ‘O1’ or ‘O2 fnoscheduleinsns’ to the
CXXFLAGS. With full ‘O2’, g++
miscompiles the division
routines. Also, do not use gcc3.0 on Sparc for compiling CLN, it
won’t work at all.
Also, please do not compile CLN with g++
using the O3
optimization level. This leads to inferior code quality.
Some newer versions of g++
require quite an amount of memory.
You might need some swap space if your machine doesn’t have 512 MB of
RAM.
By default, both a shared and a static library are built. You can build
CLN as a static (or shared) library only, by calling configure
with the option ‘disableshared’ (or ‘disablestatic’).
While shared libraries are usually more convenient to use, they may not
work on all architectures. Try disabling them if you run into linker
problems. Also, they are generally slightly slower than static
libraries so runtimecritical applications should be linked statically.
• Using the GNU MP Library: 
Up: Building the library [Index]
CLN may be configured to make use of a preinstalled gmp
library
for some lowlevel routines. Please make sure that you have at least
gmp
version 3.0 installed since earlier versions are unsupported
and likely not to work. Using gmp
is known to be quite a boost
for CLN’s performance.
By default, CLN will autodetect gmp
and use it. If you do not
want CLN to make use of a preinstalled gmp
library, then you can
explicitly specify so by calling configure
with the option
‘withoutgmp’.
If you have installed the gmp
library and its header files in
some place where the compiler cannot find it by default, you must help
configure
and specify the prefix that was used when gmp
was configured. Here is an example:
$ ./configure withgmp=/opt/gmp4.2.2
This assumes that the gmp
header files have been installed in
/opt/gmp4.2.2/include/ and the library in
/opt/gmp4.2.2/lib/. More uncommon GMP installations can be
handled by setting CPPFLAGS and LDFLAGS appropriately prior to running
configure
.
Next: Cleaning up, Previous: Building the library, Up: Installation [Index]
As with any autoconfiguring GNU software, installation is as easy as this:
$ make install
The ‘make install’ command installs the library and the include files
into public places (/usr/local/lib/ and /usr/local/include/,
if you haven’t specified a prefix
option to configure
).
This step may require superuser privileges.
If you have already built the library and wish to install it, but didn’t
specify prefix=…
at configure time, just rerun
configure
, giving it the same options as the first time, plus
the prefix=…
option.
Previous: Installing the library, Up: Installation [Index]
You can remove systemdependent files generated by make
through
$ make clean
You can remove all files generated by make
, thus reverting to a
virgin distribution of CLN, through
$ make distclean
Next: Functions on numbers, Previous: Installation, Up: Top [Index]
CLN implements the following class hierarchy:
Number cl_number <cln/number.h>   Real or complex number cl_N <cln/complex.h>   Real number cl_R <cln/real.h>  +++   Rational number Floatingpoint number cl_RA cl_F <cln/rational.h> <cln/float.h>    ++++ Integer     cl_I ShortFloat SingleFloat DoubleFloat LongFloat <cln/integer.h> cl_SF cl_FF cl_DF cl_LF <cln/sfloat.h> <cln/ffloat.h> <cln/dfloat.h> <cln/lfloat.h>
The base class cl_number
is an abstract base class.
It is not useful to declare a variable of this type except if you want
to completely disable compiletime type checking and use runtime type
checking instead.
The class cl_N
comprises real and complex numbers. There is
no special class for complex numbers since complex numbers with imaginary
part 0
are automatically converted to real numbers.
The class cl_R
comprises real numbers of different kinds. It is an
abstract class.
The class cl_RA
comprises exact real numbers: rational numbers, including
integers. There is no special class for nonintegral rational numbers
since rational numbers with denominator 1
are automatically converted
to integers.
The class cl_F
implements floatingpoint approximations to real numbers.
It is an abstract class.
• Exact numbers:  
• Floatingpoint numbers:  
• Complex numbers:  
• Conversions: 
Next: Floatingpoint numbers, Up: Ordinary number types [Index]
Some numbers are represented as exact numbers: there is no loss of information
when such a number is converted from its mathematical value to its internal
representation. On exact numbers, the elementary operations (+
,

, *
, /
, comparisons, …) compute the completely
correct result.
In CLN, the exact numbers are:
Rational numbers are always normalized to the form
numerator/denominator
where the numerator and denominator
are coprime integers and the denominator is positive. If the resulting
denominator is 1
, the rational number is converted to an integer.
Small integers (typically in the range 2^29
…2^291
,
for 32bit machines) are especially efficient, because they consume no heap
allocation. Otherwise the distinction between these immediate integers
(called “fixnums”) and heap allocated integers (called “bignums”)
is completely transparent.
Next: Complex numbers, Previous: Exact numbers, Up: Ordinary number types [Index]
Not all real numbers can be represented exactly. (There is an easy mathematical proof for this: Only a countable set of numbers can be stored exactly in a computer, even if one assumes that it has unlimited storage. But there are uncountably many real numbers.) So some approximation is needed. CLN implements ordinary floatingpoint numbers, with mantissa and exponent.
The elementary operations (+
, 
, *
, /
, …)
only return approximate results. For example, the value of the expression
(cl_F) 0.3 + (cl_F) 0.4
prints as ‘0.70000005’, not as
‘0.7’. Rounding errors like this one are inevitable when computing
with floatingpoint numbers.
Nevertheless, CLN rounds the floatingpoint results of the operations +
,

, *
, /
, sqrt
according to the “roundtoeven”
rule: It first computes the exact mathematical result and then returns the
floatingpoint number which is nearest to this. If two floatingpoint numbers
are equally distant from the ideal result, the one with a 0
in its least
significant mantissa bit is chosen.
Similarly, testing floating point numbers for equality ‘x == y’
is gambling with random errors. Better check for ‘abs(x  y) < epsilon’
for some wellchosen epsilon
.
Floating point numbers come in four flavors:
cl_SF
.
They have 1 sign bit, 8 exponent bits (including the exponent’s sign),
and 17 mantissa bits (including the “hidden” bit).
They don’t consume heap allocation.
cl_FF
.
They have 1 sign bit, 8 exponent bits (including the exponent’s sign),
and 24 mantissa bits (including the “hidden” bit).
In CLN, they are represented as IEEE singleprecision floating point numbers.
This corresponds closely to the C/C++ type ‘float’.
cl_DF
.
They have 1 sign bit, 11 exponent bits (including the exponent’s sign),
and 53 mantissa bits (including the “hidden” bit).
In CLN, they are represented as IEEE doubleprecision floating point numbers.
This corresponds closely to the C/C++ type ‘double’.
cl_LF
.
They have 1 sign bit, 32 exponent bits (including the exponent’s sign),
and n mantissa bits (including the “hidden” bit), where n >= 64.
The precision of a long float is unlimited, but once created, a long float
has a fixed precision. (No “lazy recomputation”.)
Of course, computations with long floats are more expensive than those with smaller floatingpoint formats.
CLN does not implement features like NaNs, denormalized numbers and gradual underflow. If the exponent range of some floatingpoint type is too limited for your application, choose another floatingpoint type with larger exponent range.
As a user of CLN, you can forget about the differences between the
four floatingpoint types and just declare all your floatingpoint
variables as being of type cl_F
. This has the advantage that
when you change the precision of some computation (say, from cl_DF
to cl_LF
), you don’t have to change the code, only the precision
of the initial values. Also, many transcendental functions have been
declared as returning a cl_F
when the argument is a cl_F
,
but such declarations are missing for the types cl_SF
, cl_FF
,
cl_DF
, cl_LF
. (Such declarations would be wrong if
the floating point contagion rule happened to change in the future.)
Next: Conversions, Previous: Floatingpoint numbers, Up: Ordinary number types [Index]
Complex numbers, as implemented by the class cl_N
, have a real
part and an imaginary part, both real numbers. A complex number whose
imaginary part is the exact number 0
is automatically converted
to a real number.
Complex numbers can arise from real numbers alone, for example
through application of sqrt
or transcendental functions.
Previous: Complex numbers, Up: Ordinary number types [Index]
Conversions from any class to any its superclasses (“base classes” in C++ terminology) is done automatically.
Conversions from the C builtin types ‘long’ and ‘unsigned long’
are provided for the classes cl_I
, cl_RA
, cl_R
,
cl_N
and cl_number
.
Conversions from the C builtin types ‘int’ and ‘unsigned int’
are provided for the classes cl_I
, cl_RA
, cl_R
,
cl_N
and cl_number
. However, these conversions emphasize
efficiency. On 32bit systems, their range is therefore limited:
In a declaration like ‘cl_I x = 10;’ the C++ compiler is able to
do the conversion of 10
from ‘int’ to ‘cl_I’ at compile time
already. On the other hand, code like ‘cl_I x = 1000000000;’ is
in error on 32bit machines.
So, if you want to be sure that an ‘int’ whose magnitude is not guaranteed
to be < 2^29 is correctly converted to a ‘cl_I’, first convert it to a
‘long’. Similarly, if a large ‘unsigned int’ is to be converted to a
‘cl_I’, first convert it to an ‘unsigned long’. On 64bit machines
there is no such restriction. There, conversions from arbitrary 32bit ‘int’
values always works correctly.
Conversions from the C builtin type ‘float’ are provided for the classes
cl_FF
, cl_F
, cl_R
, cl_N
and cl_number
.
Conversions from the C builtin type ‘double’ are provided for the classes
cl_DF
, cl_F
, cl_R
, cl_N
and cl_number
.
Conversions from ‘const char *’ are provided for the classes
cl_I
, cl_RA
,
cl_SF
, cl_FF
, cl_DF
, cl_LF
, cl_F
,
cl_R
, cl_N
.
The easiest way to specify a value which is outside of the range of the
C++ builtin types is therefore to specify it as a string, like this:
cl_I order_of_rubiks_cube_group = "43252003274489856000";
Note that this conversion is done at runtime, not at compiletime.
Conversions from cl_I
to the C builtin types ‘int’,
‘unsigned int’, ‘long’, ‘unsigned long’ are provided through
the functions
int cl_I_to_int (const cl_I& x)
unsigned int cl_I_to_uint (const cl_I& x)
long cl_I_to_long (const cl_I& x)
unsigned long cl_I_to_ulong (const cl_I& x)
Returns x
as element of the C type ctype. If x
is not
representable in the range of ctype, a runtime error occurs.
Conversions from the classes cl_I
, cl_RA
,
cl_SF
, cl_FF
, cl_DF
, cl_LF
, cl_F
and
cl_R
to the C builtin types ‘float’ and ‘double’ are provided through
the functions
float float_approx (const type& x)
double double_approx (const type& x)
Returns an approximation of x
of C type ctype.
If abs(x)
is too close to 0 (underflow), 0 is returned.
If abs(x)
is too large (overflow), an IEEE infinity is returned.
Conversions from any class to any of its subclasses (“derived classes” in
C++ terminology) are not provided. Instead, you can assert and check
that a value belongs to a certain subclass, and return it as element of that
class, using the ‘As’ and ‘The’ macros.
As(type)(value)
checks that value belongs to
type and returns it as such.
The(type)(value)
assumes that value belongs to
type and returns it as such. It is your responsibility to ensure
that this assumption is valid. Since macros and namespaces don’t go
together well, there is an equivalent to ‘The’: the template
‘the’.
Example:
cl_I x = …; if (!(x >= 0)) abort(); cl_I ten_x_a = The(cl_I)(expt(10,x)); // If x >= 0, 10^x is an integer. // In general, it would be a rational number. cl_I ten_x_b = the<cl_I>(expt(10,x)); // The same as above.
Next: Input/Output, Previous: Ordinary number types, Up: Top [Index]
Each of the number classes declares its mathematical operations in the
corresponding include file. For example, if your code operates with
objects of type cl_I
, it should #include <cln/integer.h>
.
Next: Elementary functions, Up: Functions on numbers [Index]
Here is how to create number objects “from nothing”.
• Constructing integers:  
• Constructing rational numbers:  
• Constructing floatingpoint numbers:  
• Constructing complex numbers: 
Next: Constructing rational numbers, Up: Constructing numbers [Index]
cl_I
objects are most easily constructed from C integers and from
strings. See Conversions.
Next: Constructing floatingpoint numbers, Previous: Constructing integers, Up: Constructing numbers [Index]
cl_RA
objects can be constructed from strings. The syntax
for rational numbers is described in Internal and printed representation.
Another standard way to produce a rational number is through application
of ‘operator /’ or ‘recip’ on integers.
Next: Constructing complex numbers, Previous: Constructing rational numbers, Up: Constructing numbers [Index]
cl_F
objects with low precision are most easily constructed from
C ‘float’ and ‘double’. See Conversions.
To construct a cl_F
with high precision, you can use the conversion
from ‘const char *’, but you have to specify the desired precision
within the string. (See Internal and printed representation.)
Example:
cl_F e = "0.271828182845904523536028747135266249775724709369996e+1_40";
will set ‘e’ to the given value, with a precision of 40 decimal digits.
The programmatic way to construct a cl_F
with high precision is
through the cl_float
conversion function, see
Conversion to floatingpoint numbers. For example, to compute
e
to 40 decimal places, first construct 1.0 to 40 decimal places
and then apply the exponential function:
float_format_t precision = float_format(40); cl_F e = exp(cl_float(1,precision));
Previous: Constructing floatingpoint numbers, Up: Constructing numbers [Index]
Nonreal cl_N
objects are normally constructed through the function
cl_N complex (const cl_R& realpart, const cl_R& imagpart)
See Elementary complex functions.
Next: Elementary rational functions, Previous: Constructing numbers, Up: Functions on numbers [Index]
Each of the classes cl_N
, cl_R
, cl_RA
, cl_I
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations:
type operator + (const type&, const type&)
Addition.
type operator  (const type&, const type&)
Subtraction.
type operator  (const type&)
Returns the negative of the argument.
type plus1 (const type& x)
Returns x + 1
.
type minus1 (const type& x)
Returns x  1
.
type operator * (const type&, const type&)
Multiplication.
type square (const type& x)
Returns x * x
.
Each of the classes cl_N
, cl_R
, cl_RA
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations:
type operator / (const type&, const type&)
Division.
type recip (const type&)
Returns the reciprocal of the argument.
The class cl_I
doesn’t define a ‘/’ operation because
in the C/C++ language this operator, applied to integral types,
denotes the ‘floor’ or ‘truncate’ operation (which one of these,
is implementation dependent). (See Rounding functions.)
Instead, cl_I
defines an “exact quotient” function:
cl_I exquo (const cl_I& x, const cl_I& y)
Checks that y
divides x
, and returns the quotient x
/y
.
The following exponentiation functions are defined:
cl_I expt_pos (const cl_I& x, const cl_I& y)
cl_RA expt_pos (const cl_RA& x, const cl_I& y)
y
must be > 0. Returns x^y
.
cl_RA expt (const cl_RA& x, const cl_I& y)
cl_R expt (const cl_R& x, const cl_I& y)
cl_N expt (const cl_N& x, const cl_I& y)
Returns x^y
.
Each of the classes cl_R
, cl_RA
, cl_I
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operation:
type abs (const type& x)
Returns the absolute value of x
.
This is x
if x >= 0
, and x
if x <= 0
.
The class cl_N
implements this as follows:
cl_R abs (const cl_N x)
Returns the absolute value of x
.
Each of the classes cl_N
, cl_R
, cl_RA
, cl_I
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operation:
type signum (const type& x)
Returns the sign of x
, in the same number format as x
.
This is defined as x / abs(x)
if x
is nonzero, and
x
if x
is zero. If x
is real, the value is either
0 or 1 or 1.
Next: Elementary complex functions, Previous: Elementary functions, Up: Functions on numbers [Index]
Each of the classes cl_RA
, cl_I
defines the following operations:
cl_I numerator (const type& x)
Returns the numerator of x
.
cl_I denominator (const type& x)
Returns the denominator of x
.
The numerator and denominator of a rational number are normalized in such a way that they have no factor in common and the denominator is positive.
Next: Comparisons, Previous: Elementary rational functions, Up: Functions on numbers [Index]
The class cl_N
defines the following operation:
cl_N complex (const cl_R& a, const cl_R& b)
Returns the complex number a+bi
, that is, the complex number with
real part a
and imaginary part b
.
Each of the classes cl_N
, cl_R
defines the following operations:
cl_R realpart (const type& x)
Returns the real part of x
.
cl_R imagpart (const type& x)
Returns the imaginary part of x
.
type conjugate (const type& x)
Returns the complex conjugate of x
.
We have the relations
x = complex(realpart(x), imagpart(x))
conjugate(x) = complex(realpart(x), imagpart(x))
Next: Rounding functions, Previous: Elementary complex functions, Up: Functions on numbers [Index]
Each of the classes cl_N
, cl_R
, cl_RA
, cl_I
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations:
bool operator == (const type&, const type&)
bool operator != (const type&, const type&)
Comparison, as in C and C++.
uint32 equal_hashcode (const type&)
Returns a 32bit hash code that is the same for any two numbers which are
the same according to ==
. This hash code depends on the number’s value,
not its type or precision.
bool zerop (const type& x)
Compare against zero: x == 0
Each of the classes cl_R
, cl_RA
, cl_I
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations:
cl_signean compare (const type& x, const type& y)
Compares x
and y
. Returns +1 if x
>y
,
1 if x
<y
, 0 if x
=y
.
bool operator <= (const type&, const type&)
bool operator < (const type&, const type&)
bool operator >= (const type&, const type&)
bool operator > (const type&, const type&)
Comparison, as in C and C++.
bool minusp (const type& x)
Compare against zero: x < 0
bool plusp (const type& x)
Compare against zero: x > 0
type max (const type& x, const type& y)
Return the maximum of x
and y
.
type min (const type& x, const type& y)
Return the minimum of x
and y
.
When a floating point number and a rational number are compared, the float
is first converted to a rational number using the function rational
.
Since a floating point number actually represents an interval of real numbers,
the result might be surprising.
For example, (cl_F)(cl_R)"1/3" == (cl_R)"1/3"
returns false because
there is no floating point number whose value is exactly 1/3
.
Next: Roots, Previous: Comparisons, Up: Functions on numbers [Index]
When a real number is to be converted to an integer, there is no “best” rounding. The desired rounding function depends on the application. The Common Lisp and ISO Lisp standards offer four rounding functions:
floor(x)
This is the largest integer <=x
.
ceiling(x)
This is the smallest integer >=x
.
truncate(x)
Among the integers between 0 and x
(inclusive) the one nearest to x
.
round(x)
The integer nearest to x
. If x
is exactly halfway between two
integers, choose the even one.
These functions have different advantages:
floor
and ceiling
are translation invariant:
floor(x+n) = floor(x) + n
and ceiling(x+n) = ceiling(x) + n
for every x
and every integer n
.
On the other hand, truncate
and round
are symmetric:
truncate(x) = truncate(x)
and round(x) = round(x)
,
and furthermore round
is unbiased: on the “average”, it rounds
down exactly as often as it rounds up.
The functions are related like this:
ceiling(m/n) = floor((m+n1)/n) = floor((m1)/n)+1
for rational numbers m/n
(m
, n
integers, n
>0), and
truncate(x) = sign(x) * floor(abs(x))
Each of the classes cl_R
, cl_RA
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations:
cl_I floor1 (const type& x)
Returns floor(x)
.
cl_I ceiling1 (const type& x)
Returns ceiling(x)
.
cl_I truncate1 (const type& x)
Returns truncate(x)
.
cl_I round1 (const type& x)
Returns round(x)
.
Each of the classes cl_R
, cl_RA
, cl_I
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations:
cl_I floor1 (const type& x, const type& y)
Returns floor(x/y)
.
cl_I ceiling1 (const type& x, const type& y)
Returns ceiling(x/y)
.
cl_I truncate1 (const type& x, const type& y)
Returns truncate(x/y)
.
cl_I round1 (const type& x, const type& y)
Returns round(x/y)
.
These functions are called ‘floor1’, … here instead of ‘floor’, …, because on some systems, system dependent include files define ‘floor’ and ‘ceiling’ as macros.
In many cases, one needs both the quotient and the remainder of a division. It is more efficient to compute both at the same time than to perform two divisions, one for quotient and the next one for the remainder. The following functions therefore return a structure containing both the quotient and the remainder. The suffix ‘2’ indicates the number of “return values”. The remainder is defined as follows:
quotient = floor(x)
,
remainder = x  quotient
,
quotient = floor(x,y)
,
remainder = x  quotient*y
,
and similarly for the other three operations.
Each of the classes cl_R
, cl_RA
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations:
struct type_div_t { cl_I quotient; type remainder; };
type_div_t floor2 (const type& x)
type_div_t ceiling2 (const type& x)
type_div_t truncate2 (const type& x)
type_div_t round2 (const type& x)
Each of the classes cl_R
, cl_RA
, cl_I
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations:
struct type_div_t { cl_I quotient; type remainder; };
type_div_t floor2 (const type& x, const type& y)
type_div_t ceiling2 (const type& x, const type& y)
type_div_t truncate2 (const type& x, const type& y)
type_div_t round2 (const type& x, const type& y)
Sometimes, one wants the quotient as a floatingpoint number (of the same format as the argument, if the argument is a float) instead of as an integer. The prefix ‘f’ indicates this.
Each of the classes
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations:
type ffloor (const type& x)
type fceiling (const type& x)
type ftruncate (const type& x)
type fround (const type& x)
and similarly for class cl_R
, but with return type cl_F
.
The class cl_R
defines the following operations:
cl_F ffloor (const type& x, const type& y)
cl_F fceiling (const type& x, const type& y)
cl_F ftruncate (const type& x, const type& y)
cl_F fround (const type& x, const type& y)
These functions also exist in versions which return both the quotient and the remainder. The suffix ‘2’ indicates this.
Each of the classes
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations:
struct type_fdiv_t { type quotient; type remainder; };
type_fdiv_t ffloor2 (const type& x)
type_fdiv_t fceiling2 (const type& x)
type_fdiv_t ftruncate2 (const type& x)
type_fdiv_t fround2 (const type& x)
and similarly for class cl_R
, but with quotient type cl_F
.
The class cl_R
defines the following operations:
struct type_fdiv_t { cl_F quotient; cl_R remainder; };
type_fdiv_t ffloor2 (const type& x, const type& y)
type_fdiv_t fceiling2 (const type& x, const type& y)
type_fdiv_t ftruncate2 (const type& x, const type& y)
type_fdiv_t fround2 (const type& x, const type& y)
Other applications need only the remainder of a division. The remainder of ‘floor’ and ‘ffloor’ is called ‘mod’ (abbreviation of “modulo”). The remainder ‘truncate’ and ‘ftruncate’ is called ‘rem’ (abbreviation of “remainder”).
mod(x,y) = floor2(x,y).remainder = x  floor(x/y)*y
rem(x,y) = truncate2(x,y).remainder = x  truncate(x/y)*y
If x
and y
are both >= 0, mod(x,y) = rem(x,y) >= 0
.
In general, mod(x,y)
has the sign of y
or is zero,
and rem(x,y)
has the sign of x
or is zero.
The classes cl_R
, cl_I
define the following operations:
type mod (const type& x, const type& y)
type rem (const type& x, const type& y)
Next: Transcendental functions, Previous: Rounding functions, Up: Functions on numbers [Index]
Each of the classes cl_R
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operation:
type sqrt (const type& x)
x
must be >= 0. This function returns the square root of x
,
normalized to be >= 0. If x
is the square of a rational number,
sqrt(x)
will be a rational number, else it will return a
floatingpoint approximation.
The classes cl_RA
, cl_I
define the following operation:
bool sqrtp (const type& x, type* root)
This tests whether x
is a perfect square. If so, it returns true
and the exact square root in *root
, else it returns false.
Furthermore, for integers, similarly:
bool isqrt (const type& x, type* root)
x
should be >= 0. This function sets *root
to
floor(sqrt(x))
and returns the same value as sqrtp
:
the boolean value (expt(*root,2) == x)
.
For n
th roots, the classes cl_RA
, cl_I
define the following operation:
bool rootp (const type& x, const cl_I& n, type* root)
x
must be >= 0. n
must be > 0.
This tests whether x
is an n
th power of a rational number.
If so, it returns true and the exact root in *root
, else it returns
false.
The only square root function which accepts negative numbers is the one
for class cl_N
:
cl_N sqrt (const cl_N& z)
Returns the square root of z
, as defined by the formula
sqrt(z) = exp(log(z)/2)
. Conversion to a floatingpoint type
or to a complex number are done if necessary. The range of the result is the
right half plane realpart(sqrt(z)) >= 0
including the positive imaginary axis and 0, but excluding
the negative imaginary axis.
The result is an exact number only if z
is an exact number.
Next: Functions on integers, Previous: Roots, Up: Functions on numbers [Index]
The transcendental functions return an exact result if the argument
is exact and the result is exact as well. Otherwise they must return
inexact numbers even if the argument is exact.
For example, cos(0) = 1
returns the rational number 1
.
• Exponential and logarithmic functions:  
• Trigonometric functions:  
• Hyperbolic functions:  
• Euler gamma:  
• Riemann zeta: 
Next: Trigonometric functions, Up: Transcendental functions [Index]
cl_R exp (const cl_R& x)
cl_N exp (const cl_N& x)
Returns the exponential function of x
. This is e^x
where
e
is the base of the natural logarithms. The range of the result
is the entire complex plane excluding 0.
cl_R ln (const cl_R& x)
x
must be > 0. Returns the (natural) logarithm of x.
cl_N log (const cl_N& x)
Returns the (natural) logarithm of x. If x
is real and positive,
this is ln(x)
. In general, log(x) = log(abs(x)) + i*phase(x)
.
The range of the result is the strip in the complex plane
pi < imagpart(log(x)) <= pi
.
cl_R phase (const cl_N& x)
Returns the angle part of x
in its polar representation as a
complex number. That is, phase(x) = atan(realpart(x),imagpart(x))
.
This is also the imaginary part of log(x)
.
The range of the result is the interval pi < phase(x) <= pi
.
The result will be an exact number only if zerop(x)
or
if x
is real and positive.
cl_R log (const cl_R& a, const cl_R& b)
a
and b
must be > 0. Returns the logarithm of a
with
respect to base b
. log(a,b) = ln(a)/ln(b)
.
The result can be exact only if a = 1
or if a
and b
are both rational.
cl_N log (const cl_N& a, const cl_N& b)
Returns the logarithm of a
with respect to base b
.
log(a,b) = log(a)/log(b)
.
cl_N expt (const cl_N& x, const cl_N& y)
Exponentiation: Returns x^y = exp(y*log(x))
.
The constant e = exp(1) = 2.71828… is returned by the following functions:
cl_F exp1 (float_format_t f)
Returns e as a float of format f
.
cl_F exp1 (const cl_F& y)
Returns e in the float format of y
.
cl_F exp1 (void)
Returns e as a float of format default_float_format
.
Next: Hyperbolic functions, Previous: Exponential and logarithmic functions, Up: Transcendental functions [Index]
cl_R sin (const cl_R& x)
Returns sin(x)
. The range of the result is the interval
1 <= sin(x) <= 1
.
cl_N sin (const cl_N& z)
Returns sin(z)
. The range of the result is the entire complex plane.
cl_R cos (const cl_R& x)
Returns cos(x)
. The range of the result is the interval
1 <= cos(x) <= 1
.
cl_N cos (const cl_N& x)
Returns cos(z)
. The range of the result is the entire complex plane.
struct cos_sin_t { cl_R cos; cl_R sin; };
cos_sin_t cos_sin (const cl_R& x)
Returns both sin(x)
and cos(x)
. This is more efficient than
computing them separately. The relation cos^2 + sin^2 = 1
will
hold only approximately.
cl_R tan (const cl_R& x)
cl_N tan (const cl_N& x)
Returns tan(x) = sin(x)/cos(x)
.
cl_N cis (const cl_R& x)
cl_N cis (const cl_N& x)
Returns exp(i*x)
. The name ‘cis’ means “cos + i sin”, because
e^(i*x) = cos(x) + i*sin(x)
.
cl_N asin (const cl_N& z)
Returns arcsin(z)
. This is defined as
arcsin(z) = log(iz+sqrt(1z^2))/i
and satisfies
arcsin(z) = arcsin(z)
.
The range of the result is the strip in the complex domain
pi/2 <= realpart(arcsin(z)) <= pi/2
, excluding the numbers
with realpart = pi/2
and imagpart < 0
and the numbers
with realpart = pi/2
and imagpart > 0
.
cl_N acos (const cl_N& z)
Returns arccos(z)
. This is defined as
arccos(z) = pi/2  arcsin(z) = log(z+i*sqrt(1z^2))/i
and satisfies arccos(z) = pi  arccos(z)
.
The range of the result is the strip in the complex domain
0 <= realpart(arcsin(z)) <= pi
, excluding the numbers
with realpart = 0
and imagpart < 0
and the numbers
with realpart = pi
and imagpart > 0
.
cl_R atan (const cl_R& x, const cl_R& y)
Returns the angle of the polar representation of the complex number
x+iy
. This is atan(y/x)
if x>0
. The range of
the result is the interval pi < atan(x,y) <= pi
. The result will
be an exact number only if x > 0
and y
is the exact 0
.
WARNING: In Common Lisp, this function is called as (atan y x)
,
with reversed order of arguments.
cl_R atan (const cl_R& x)
Returns arctan(x)
. This is the same as atan(1,x)
. The range
of the result is the interval pi/2 < atan(x) < pi/2
. The result
will be an exact number only if x
is the exact 0
.
cl_N atan (const cl_N& z)
Returns arctan(z)
. This is defined as
arctan(z) = (log(1+iz)log(1iz)) / 2i
and satisfies
arctan(z) = arctan(z)
. The range of the result is
the strip in the complex domain
pi/2 <= realpart(arctan(z)) <= pi/2
, excluding the numbers
with realpart = pi/2
and imagpart >= 0
and the numbers
with realpart = pi/2
and imagpart <= 0
.
Archimedes’ constant pi = 3.14… is returned by the following functions:
cl_F pi (float_format_t f)
Returns pi as a float of format f
.
cl_F pi (const cl_F& y)
Returns pi in the float format of y
.
cl_F pi (void)
Returns pi as a float of format default_float_format
.
Next: Euler gamma, Previous: Trigonometric functions, Up: Transcendental functions [Index]
cl_R sinh (const cl_R& x)
Returns sinh(x)
.
cl_N sinh (const cl_N& z)
Returns sinh(z)
. The range of the result is the entire complex plane.
cl_R cosh (const cl_R& x)
Returns cosh(x)
. The range of the result is the interval
cosh(x) >= 1
.
cl_N cosh (const cl_N& z)
Returns cosh(z)
. The range of the result is the entire complex plane.
struct cosh_sinh_t { cl_R cosh; cl_R sinh; };
cosh_sinh_t cosh_sinh (const cl_R& x)
Returns both sinh(x)
and cosh(x)
. This is more efficient than
computing them separately. The relation cosh^2  sinh^2 = 1
will
hold only approximately.
cl_R tanh (const cl_R& x)
cl_N tanh (const cl_N& x)
Returns tanh(x) = sinh(x)/cosh(x)
.
cl_N asinh (const cl_N& z)
Returns arsinh(z)
. This is defined as
arsinh(z) = log(z+sqrt(1+z^2))
and satisfies
arsinh(z) = arsinh(z)
.
The range of the result is the strip in the complex domain
pi/2 <= imagpart(arsinh(z)) <= pi/2
, excluding the numbers
with imagpart = pi/2
and realpart > 0
and the numbers
with imagpart = pi/2
and realpart < 0
.
cl_N acosh (const cl_N& z)
Returns arcosh(z)
. This is defined as
arcosh(z) = 2*log(sqrt((z+1)/2)+sqrt((z1)/2))
.
The range of the result is the halfstrip in the complex domain
pi < imagpart(arcosh(z)) <= pi, realpart(arcosh(z)) >= 0
,
excluding the numbers with realpart = 0
and pi < imagpart < 0
.
cl_N atanh (const cl_N& z)
Returns artanh(z)
. This is defined as
artanh(z) = (log(1+z)log(1z)) / 2
and satisfies
artanh(z) = artanh(z)
. The range of the result is
the strip in the complex domain
pi/2 <= imagpart(artanh(z)) <= pi/2
, excluding the numbers
with imagpart = pi/2
and realpart <= 0
and the numbers
with imagpart = pi/2
and realpart >= 0
.
Next: Riemann zeta, Previous: Hyperbolic functions, Up: Transcendental functions [Index]
Euler’s constant C = 0.577… is returned by the following functions:
cl_F eulerconst (float_format_t f)
Returns Euler’s constant as a float of format f
.
cl_F eulerconst (const cl_F& y)
Returns Euler’s constant in the float format of y
.
cl_F eulerconst (void)
Returns Euler’s constant as a float of format default_float_format
.
Catalan’s constant G = 0.915… is returned by the following functions:
cl_F catalanconst (float_format_t f)
Returns Catalan’s constant as a float of format f
.
cl_F catalanconst (const cl_F& y)
Returns Catalan’s constant in the float format of y
.
cl_F catalanconst (void)
Returns Catalan’s constant as a float of format default_float_format
.
Previous: Euler gamma, Up: Transcendental functions [Index]
Riemann’s zeta function at an integral point s>1
is returned by the
following functions:
cl_F zeta (int s, float_format_t f)
Returns Riemann’s zeta function at s
as a float of format f
.
cl_F zeta (int s, const cl_F& y)
Returns Riemann’s zeta function at s
in the float format of y
.
cl_F zeta (int s)
Returns Riemann’s zeta function at s
as a float of format
default_float_format
.
Next: Functions on floatingpoint numbers, Previous: Transcendental functions, Up: Functions on numbers [Index]
• Logical functions:  
• Number theoretic functions:  
• Combinatorial functions: 
Next: Number theoretic functions, Up: Functions on integers [Index]
Integers, when viewed as in two’s complement notation, can be thought as infinite bit strings where the bits’ values eventually are constant. For example,
17 = ......00010001 6 = ......11111010
The logical operations view integers as such bit strings and operate on each of the bit positions in parallel.
cl_I lognot (const cl_I& x)
cl_I operator ~ (const cl_I& x)
Logical not, like ~x
in C. This is the same as 1x
.
cl_I logand (const cl_I& x, const cl_I& y)
cl_I operator & (const cl_I& x, const cl_I& y)
Logical and, like x & y
in C.
cl_I logior (const cl_I& x, const cl_I& y)
cl_I operator  (const cl_I& x, const cl_I& y)
Logical (inclusive) or, like x  y
in C.
cl_I logxor (const cl_I& x, const cl_I& y)
cl_I operator ^ (const cl_I& x, const cl_I& y)
Exclusive or, like x ^ y
in C.
cl_I logeqv (const cl_I& x, const cl_I& y)
Bitwise equivalence, like ~(x ^ y)
in C.
cl_I lognand (const cl_I& x, const cl_I& y)
Bitwise not and, like ~(x & y)
in C.
cl_I lognor (const cl_I& x, const cl_I& y)
Bitwise not or, like ~(x  y)
in C.
cl_I logandc1 (const cl_I& x, const cl_I& y)
Logical and, complementing the first argument, like ~x & y
in C.
cl_I logandc2 (const cl_I& x, const cl_I& y)
Logical and, complementing the second argument, like x & ~y
in C.
cl_I logorc1 (const cl_I& x, const cl_I& y)
Logical or, complementing the first argument, like ~x  y
in C.
cl_I logorc2 (const cl_I& x, const cl_I& y)
Logical or, complementing the second argument, like x  ~y
in C.
These operations are all available though the function
cl_I boole (cl_boole op, const cl_I& x, const cl_I& y)
where op
must have one of the 16 values (each one stands for a function
which combines two bits into one bit): boole_clr
, boole_set
,
boole_1
, boole_2
, boole_c1
, boole_c2
,
boole_and
, boole_ior
, boole_xor
, boole_eqv
,
boole_nand
, boole_nor
, boole_andc1
, boole_andc2
,
boole_orc1
, boole_orc2
.
Other functions that view integers as bit strings:
bool logtest (const cl_I& x, const cl_I& y)
Returns true if some bit is set in both x
and y
, i.e. if
logand(x,y) != 0
.
bool logbitp (const cl_I& n, const cl_I& x)
Returns true if the n
th bit (from the right) of x
is set.
Bit 0 is the least significant bit.
uintC logcount (const cl_I& x)
Returns the number of one bits in x
, if x
>= 0, or
the number of zero bits in x
, if x
< 0.
The following functions operate on intervals of bits in integers. The type
struct cl_byte { uintC size; uintC position; };
represents the bit interval containing the bits
position
…position+size1
of an integer.
The constructor cl_byte(size,position)
constructs a cl_byte
.
cl_I ldb (const cl_I& n, const cl_byte& b)
extracts the bits of n
described by the bit interval b
and returns them as a nonnegative integer with b.size
bits.
bool ldb_test (const cl_I& n, const cl_byte& b)
Returns true if some bit described by the bit interval b
is set in
n
.
cl_I dpb (const cl_I& newbyte, const cl_I& n, const cl_byte& b)
Returns n
, with the bits described by the bit interval b
replaced by newbyte
. Only the lowest b.size
bits of
newbyte
are relevant.
The functions ldb
and dpb
implicitly shift. The following
functions are their counterparts without shifting:
cl_I mask_field (const cl_I& n, const cl_byte& b)
returns an integer with the bits described by the bit interval b
copied from the corresponding bits in n
, the other bits zero.
cl_I deposit_field (const cl_I& newbyte, const cl_I& n, const cl_byte& b)
returns an integer where the bits described by the bit interval b
come from newbyte
and the other bits come from n
.
The following relations hold:
ldb (n, b) = mask_field(n, b) >> b.position
,
dpb (newbyte, n, b) = deposit_field (newbyte << b.position, n, b)
,
deposit_field(newbyte,n,b) = n ^ mask_field(n,b) ^ mask_field(new_byte,b)
.
The following operations on integers as bit strings are efficient shortcuts for common arithmetic operations:
bool oddp (const cl_I& x)
Returns true if the least significant bit of x
is 1. Equivalent to
mod(x,2) != 0
.
bool evenp (const cl_I& x)
Returns true if the least significant bit of x
is 0. Equivalent to
mod(x,2) == 0
.
cl_I operator << (const cl_I& x, const cl_I& n)
Shifts x
by n
bits to the left. n
should be >=0.
Equivalent to x * expt(2,n)
.
cl_I operator >> (const cl_I& x, const cl_I& n)
Shifts x
by n
bits to the right. n
should be >=0.
Bits shifted out to the right are thrown away.
Equivalent to floor(x / expt(2,n))
.
cl_I ash (const cl_I& x, const cl_I& y)
Shifts x
by y
bits to the left (if y
>=0) or
by y
bits to the right (if y
<=0). In other words, this
returns floor(x * expt(2,y))
.
uintC integer_length (const cl_I& x)
Returns the number of bits (excluding the sign bit) needed to represent x
in two’s complement notation. This is the smallest n >= 0 such that
2^n <= x < 2^n. If x > 0, this is the unique n > 0 such that
2^(n1) <= x < 2^n.
uintC ord2 (const cl_I& x)
x
must be nonzero. This function returns the number of 0 bits at the
right of x
in two’s complement notation. This is the largest n >= 0
such that 2^n divides x
.
uintC power2p (const cl_I& x)
x
must be > 0. This function checks whether x
is a power of 2.
If x
= 2^(n1), it returns n. Else it returns 0.
(See also the function logp
.)
Next: Combinatorial functions, Previous: Logical functions, Up: Functions on integers [Index]
uint32 gcd (unsigned long a, unsigned long b)
cl_I gcd (const cl_I& a, const cl_I& b)
This function returns the greatest common divisor of a
and b
,
normalized to be >= 0.
cl_I xgcd (const cl_I& a, const cl_I& b, cl_I* u, cl_I* v)
This function (“extended gcd”) returns the greatest common divisor g
of
a
and b
and at the same time the representation of g
as an integral linear combination of a
and b
:
u
and v
with u*a+v*b = g
, g
>= 0.
u
and v
will be normalized to be of smallest possible absolute
value, in the following sense: If a
and b
are nonzero, and
abs(a) != abs(b)
, u
and v
will satisfy the inequalities
abs(u) <= abs(b)/(2*g)
, abs(v) <= abs(a)/(2*g)
.
cl_I lcm (const cl_I& a, const cl_I& b)
This function returns the least common multiple of a
and b
,
normalized to be >= 0.
bool logp (const cl_I& a, const cl_I& b, cl_RA* l)
bool logp (const cl_RA& a, const cl_RA& b, cl_RA* l)
a
must be > 0. b
must be >0 and != 1. If log(a,b) is
rational number, this function returns true and sets *l = log(a,b), else
it returns false.
int jacobi (signed long a, signed long b)
int jacobi (const cl_I& a, const cl_I& b)
Returns the Jacobi symbol
(a/b),
a,b
must be integers, b>0
and odd. The result is 0
iff gcd(a,b)>1.
bool isprobprime (const cl_I& n)
Returns true if n
is a small prime or passes the MillerRabin
primality test. The probability of a false positive is 1:10^30.
cl_I nextprobprime (const cl_R& x)
Returns the smallest probable prime >=x
.
Previous: Number theoretic functions, Up: Functions on integers [Index]
cl_I factorial (uintL n)
n
must be a small integer >= 0. This function returns the factorial
n
! = 1*2*…*n
.
cl_I doublefactorial (uintL n)
n
must be a small integer >= 0. This function returns the
doublefactorial n
!! = 1*3*…*n
or
n
!! = 2*4*…*n
, respectively.
cl_I binomial (uintL n, uintL k)
n
and k
must be small integers >= 0. This function returns the
binomial coefficient
for 0 <= k <= n, 0 else.
Next: Conversion functions, Previous: Functions on integers, Up: Functions on numbers [Index]
Recall that a floatingpoint number consists of a sign s
, an
exponent e
and a mantissa m
. The value of the number is
(1)^s * 2^e * m
.
Each of the classes
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines the following operations.
type scale_float (const type& x, sintC delta)
type scale_float (const type& x, const cl_I& delta)
Returns x*2^delta
. This is more efficient than an explicit multiplication
because it copies x
and modifies the exponent.
The following functions provide an abstract interface to the underlying representation of floatingpoint numbers.
sintE float_exponent (const type& x)
Returns the exponent e
of x
.
For x = 0.0
, this is 0. For x
nonzero, this is the unique
integer with 2^(e1) <= abs(x) < 2^e
.
sintL float_radix (const type& x)
Returns the base of the floatingpoint representation. This is always 2
.
type float_sign (const type& x)
Returns the sign s
of x
as a float. The value is 1 for
x
>= 0, 1 for x
< 0.
uintC float_digits (const type& x)
Returns the number of mantissa bits in the floatingpoint representation
of x
, including the hidden bit. The value only depends on the type
of x
, not on its value.
uintC float_precision (const type& x)
Returns the number of significant mantissa bits in the floatingpoint
representation of x
. Since denormalized numbers are not supported,
this is the same as float_digits(x)
if x
is nonzero, and
0 if x
= 0.
The complete internal representation of a float is encoded in the type
decoded_float
(or decoded_sfloat
, decoded_ffloat
,
decoded_dfloat
, decoded_lfloat
, respectively), defined by
struct decoded_typefloat { type mantissa; cl_I exponent; type sign; };
and returned by the function
decoded_typefloat decode_float (const type& x)
For x
nonzero, this returns (1)^s
, e
, m
with
x = (1)^s * 2^e * m
and 0.5 <= m < 1.0
. For x
= 0,
it returns (1)^s
=1, e
=0, m
=0.
e
is the same as returned by the function float_exponent
.
A complete decoding in terms of integers is provided as type
struct cl_idecoded_float { cl_I mantissa; cl_I exponent; cl_I sign; };
by the following function:
cl_idecoded_float integer_decode_float (const type& x)
For x
nonzero, this returns (1)^s
, e
, m
with
x = (1)^s * 2^e * m
and m
an integer with float_digits(x)
bits. For x
= 0, it returns (1)^s
=1, e
=0, m
=0.
WARNING: The exponent e
is not the same as the one returned by
the functions decode_float
and float_exponent
.
Some other function, implemented only for class cl_F
:
cl_F float_sign (const cl_F& x, const cl_F& y)
This returns a floating point number whose precision and absolute value
is that of y
and whose sign is that of x
. If x
is
zero, it is treated as positive. Same for y
.
Next: Random number generators, Previous: Functions on floatingpoint numbers, Up: Functions on numbers [Index]
• Conversion to floatingpoint numbers:  
• Conversion to rational numbers: 
Next: Conversion to rational numbers, Up: Conversion functions [Index]
The type float_format_t
describes a floatingpoint format.
float_format_t float_format (uintE n)
Returns the smallest float format which guarantees at least n
decimal digits in the mantissa (after the decimal point).
float_format_t float_format (const cl_F& x)
Returns the floating point format of x
.
float_format_t default_float_format
Global variable: the default float format used when converting rational numbers to floats.
To convert a real number to a float, each of the types
cl_R
, cl_F
, cl_I
, cl_RA
,
int
, unsigned int
, float
, double
defines the following operations:
cl_F cl_float (const type&x, float_format_t f)
Returns x
as a float of format f
.
cl_F cl_float (const type&x, const cl_F& y)
Returns x
in the float format of y
.
cl_F cl_float (const type&x)
Returns x
as a float of format default_float_format
if
it is an exact number, or x
itself if it is already a float.
Of course, converting a number to a float can lose precision.
Every floatingpoint format has some characteristic numbers:
cl_F most_positive_float (float_format_t f)
Returns the largest (most positive) floating point number in float format f
.
cl_F most_negative_float (float_format_t f)
Returns the smallest (most negative) floating point number in float format f
.
cl_F least_positive_float (float_format_t f)
Returns the least positive floating point number (i.e. > 0 but closest to 0)
in float format f
.
cl_F least_negative_float (float_format_t f)
Returns the least negative floating point number (i.e. < 0 but closest to 0)
in float format f
.
cl_F float_epsilon (float_format_t f)
Returns the smallest floating point number e > 0 such that 1+e != 1
.
cl_F float_negative_epsilon (float_format_t f)
Returns the smallest floating point number e > 0 such that 1e != 1
.
Previous: Conversion to floatingpoint numbers, Up: Conversion functions [Index]
Each of the classes cl_R
, cl_RA
, cl_F
defines the following operation:
cl_RA rational (const type& x)
Returns the value of x
as an exact number. If x
is already
an exact number, this is x
. If x
is a floatingpoint number,
the value is a rational number whose denominator is a power of 2.
In order to convert back, say, (cl_F)(cl_R)"1/3"
to 1/3
, there is
the function
cl_RA rationalize (const cl_R& x)
If x
is a floatingpoint number, it actually represents an interval
of real numbers, and this function returns the rational number with
smallest denominator (and smallest numerator, in magnitude)
which lies in this interval.
If x
is already an exact number, this function returns x
.
If x
is any float, one has
cl_float(rational(x),x) = x
cl_float(rationalize(x),x) = x
Next: Modifying operators, Previous: Conversion functions, Up: Functions on numbers [Index]
A random generator is a machine which produces (pseudo)random numbers.
The include file <cln/random.h>
defines a class random_state
which contains the state of a random generator. If you make a copy
of the random number generator, the original one and the copy will produce
the same sequence of random numbers.
The following functions return (pseudo)random numbers in different formats. Calling one of these modifies the state of the random number generator in a complicated but deterministic way.
random_state default_random_state
contains a default random number generator. It is used when the functions
below are called without random_state
argument.
uint32 random32 (random_state& randomstate)
uint32 random32 ()
Returns a random unsigned 32bit number. All bits are equally random.
cl_I random_I (random_state& randomstate, const cl_I& n)
cl_I random_I (const cl_I& n)
n
must be an integer > 0. This function returns a random integer x
in the range 0 <= x < n
.
cl_F random_F (random_state& randomstate, const cl_F& n)
cl_F random_F (const cl_F& n)
n
must be a float > 0. This function returns a random floatingpoint
number of the same format as n
in the range 0 <= x < n
.
cl_R random_R (random_state& randomstate, const cl_R& n)
cl_R random_R (const cl_R& n)
Behaves like random_I
if n
is an integer and like random_F
if n
is a float.
Previous: Random number generators, Up: Functions on numbers [Index]
The modifying C/C++ operators +=
, =
, *=
, /=
,
&=
, =
, ^=
, <<=
, >>=
are all available.
For the classes cl_N
, cl_R
, cl_RA
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
:
type& operator += (type&, const type&)
type& operator = (type&, const type&)
type& operator *= (type&, const type&)
type& operator /= (type&, const type&)
For the class cl_I
:
type& operator += (type&, const type&)
type& operator = (type&, const type&)
type& operator *= (type&, const type&)
type& operator &= (type&, const type&)
type& operator = (type&, const type&)
type& operator ^= (type&, const type&)
type& operator <<= (type&, const type&)
type& operator >>= (type&, const type&)
For the classes cl_N
, cl_R
, cl_RA
, cl_I
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
:
type& operator ++ (type& x)
The prefix operator ++x
.
void operator ++ (type& x, int)
The postfix operator x++
.
type& operator  (type& x)
The prefix operator x
.
void operator  (type& x, int)
The postfix operator x
.
Note that by using these modifying operators, you don’t gain efficiency: In CLN ‘x += y;’ is exactly the same as ‘x = x+y;’, not more efficient.
Next: Rings, Previous: Functions on numbers, Up: Top [Index]
• Internal and printed representation:  
• Input functions:  
• Output functions: 
Next: Input functions, Up: Input/Output [Index]
All computations deal with the internal representations of the numbers.
Every number has an external representation as a sequence of ASCII characters. Several external representations may denote the same number, for example, "20.0" and "20.000".
Converting an internal to an external representation is called “printing”,
converting an external to an internal representation is called “reading”.
In CLN, it is always true that conversion of an internal to an external
representation and then back to an internal representation will yield the
same internal representation. Symbolically: read(print(x)) == x
.
This is called “printread consistency”.
Different types of numbers have different external representations (case is insignificant):
External representation: sign{digit}+. The reader also accepts the
Common Lisp syntaxes sign{digit}+.
with a trailing dot
for decimal integers
and the #nR
, #b
, #o
, #x
prefixes.
External representation: sign{digit}+/
{digit}+.
The #nR
, #b
, #o
, #x
prefixes are allowed
here as well.
External representation: sign{digit}*exponent or
sign{digit}*.
{digit}*exponent or
sign{digit}*.
{digit}+. A precision specifier
of the form _prec may be appended. There must be at least
one digit in the nonexponent part. The exponent has the syntax
expmarker expsign {digit}+.
The exponent marker is
or ‘e’, which denotes a default float format. The precision specifying suffix has the syntax _prec where prec denotes the number of valid mantissa digits (in decimal, excluding leading zeroes), cf. also function ‘float_format’.
External representation:
realpart+imagparti
. Of course,
if imagpart is negative, its printed representation begins with
a ‘’, and the ‘+’ between realpart and imagpart
may be omitted. Note that this notation cannot be used when the imagpart
is rational and the rational number’s base is >18, because the ‘i’
is then read as a digit.
#C(realpart imagpart)
.
Next: Output functions, Previous: Internal and printed representation, Up: Input/Output [Index]
Including <cln/io.h>
defines flexible input functions:
cl_N read_complex (std::istream& stream, const cl_read_flags& flags)
cl_R read_real (std::istream& stream, const cl_read_flags& flags)
cl_F read_float (std::istream& stream, const cl_read_flags& flags)
cl_RA read_rational (std::istream& stream, const cl_read_flags& flags)
cl_I read_integer (std::istream& stream, const cl_read_flags& flags)
Reads a number from stream
. The flags
are parameters which
affect the input syntax. Whitespace before the number is silently skipped.
cl_N read_complex (const cl_read_flags& flags, const char * string, const char * string_limit, const char * * end_of_parse)
cl_R read_real (const cl_read_flags& flags, const char * string, const char * string_limit, const char * * end_of_parse)
cl_F read_float (const cl_read_flags& flags, const char * string, const char * string_limit, const char * * end_of_parse)
cl_RA read_rational (const cl_read_flags& flags, const char * string, const char * string_limit, const char * * end_of_parse)
cl_I read_integer (const cl_read_flags& flags, const char * string, const char * string_limit, const char * * end_of_parse)
Reads a number from a string in memory. The flags
are parameters which
affect the input syntax. The string starts at string
and ends at
string_limit
(exclusive limit). string_limit
may also be
NULL
, denoting the entire string, i.e. equivalent to
string_limit = string + strlen(string)
. If end_of_parse
is
NULL
, the string in memory must contain exactly one number and nothing
more, else an exception will be thrown. If end_of_parse
is not NULL
, *end_of_parse
will be assigned a pointer past
the last parsed character (i.e. string_limit
if nothing came after
the number). Whitespace is not allowed.
The structure cl_read_flags
contains the following fields:
cl_read_syntax_t syntax
The possible results of the read operation. Possible values are
syntax_number
, syntax_real
, syntax_rational
,
syntax_integer
, syntax_float
, syntax_sfloat
,
syntax_ffloat
, syntax_dfloat
, syntax_lfloat
.
cl_read_lsyntax_t lsyntax
Specifies the languagedependent syntax variant for the read operation. Possible values are
lsyntax_standard
accept standard algebraic notation only, no complex numbers,
lsyntax_algebraic
accept the algebraic notation x+yi
for complex numbers,
lsyntax_commonlisp
accept the #b
, #o
, #x
syntaxes for binary, octal,
hexadecimal numbers,
#baseR
for rational numbers in a given base,
#c(realpart imagpart)
for complex numbers,
lsyntax_all
accept all of these extensions.
unsigned int rational_base
The base in which rational numbers are read.
float_format_t float_flags.default_float_format
The float format used when reading floats with exponent marker ‘e’.
float_format_t float_flags.default_lfloat_format
The float format used when reading floats with exponent marker ‘l’.
bool float_flags.mantissa_dependent_float_format
When this flag is true, floats specified with more digits than corresponding to the exponent marker they contain, but without _nnn suffix, will get a precision corresponding to their number of significant digits.
Previous: Input functions, Up: Input/Output [Index]
Including <cln/io.h>
defines a number of simple output functions
that write to std::ostream&
:
void fprintchar (std::ostream& stream, char c)
Prints the character x
literally on the stream
.
void fprint (std::ostream& stream, const char * string)
Prints the string
literally on the stream
.
void fprintdecimal (std::ostream& stream, int x)
void fprintdecimal (std::ostream& stream, const cl_I& x)
Prints the integer x
in decimal on the stream
.
void fprintbinary (std::ostream& stream, const cl_I& x)
Prints the integer x
in binary (base 2, without prefix)
on the stream
.
void fprintoctal (std::ostream& stream, const cl_I& x)
Prints the integer x
in octal (base 8, without prefix)
on the stream
.
void fprinthexadecimal (std::ostream& stream, const cl_I& x)
Prints the integer x
in hexadecimal (base 16, without prefix)
on the stream
.
Each of the classes cl_N
, cl_R
, cl_RA
, cl_I
,
cl_F
, cl_SF
, cl_FF
, cl_DF
, cl_LF
defines, in <cln/type_io.h>
, the following output functions:
void fprint (std::ostream& stream, const type& x)
std::ostream& operator<< (std::ostream& stream, const type& x)
Prints the number x
on the stream
. The output may depend
on the global printer settings in the variable default_print_flags
.
The ostream
flags and settings (flags, width and locale) are
ignored.
The most flexible output function, defined in <cln/type_io.h>
,
are the following:
void print_complex (std::ostream& stream, const cl_print_flags& flags, const cl_N& z); void print_real (std::ostream& stream, const cl_print_flags& flags, const cl_R& z); void print_float (std::ostream& stream, const cl_print_flags& flags, const cl_F& z); void print_rational (std::ostream& stream, const cl_print_flags& flags, const cl_RA& z); void print_integer (std::ostream& stream, const cl_print_flags& flags, const cl_I& z);
Prints the number x
on the stream
. The flags
are
parameters which affect the output.
The structure type cl_print_flags
contains the following fields:
unsigned int rational_base
The base in which rational numbers are printed. Default is 10
.
bool rational_readably
If this flag is true, rational numbers are printed with radix specifiers in
Common Lisp syntax (#nR
or #b
or #o
or #x
prefixes, trailing dot). Default is false.
bool float_readably
If this flag is true, type specific exponent markers have precedence over ’E’. Default is false.
float_format_t default_float_format
Floating point numbers of this format will be printed using the ’E’ exponent
marker. Default is float_format_ffloat
.
bool complex_readably
If this flag is true, complex numbers will be printed using the Common Lisp
syntax #C(realpart imagpart)
. Default is false.
cl_string univpoly_varname
Univariate polynomials with no explicit indeterminate name will be printed
using this variable name. Default is "x"
.
The global variable default_print_flags
contains the default values,
used by the function fprint
.
Next: Modular integers, Previous: Input/Output, Up: Top [Index]
CLN has a class of abstract rings.
Ring cl_ring <cln/ring.h>
Rings can be compared for equality:
bool operator== (const cl_ring&, const cl_ring&)
bool operator!= (const cl_ring&, const cl_ring&)
These compare two rings for equality.
Given a ring R
, the following members can be used.
void R>fprint (std::ostream& stream, const cl_ring_element& x)
bool R>equal (const cl_ring_element& x, const cl_ring_element& y)
cl_ring_element R>zero ()
bool R>zerop (const cl_ring_element& x)
cl_ring_element R>plus (const cl_ring_element& x, const cl_ring_element& y)
cl_ring_element R>minus (const cl_ring_element& x, const cl_ring_element& y)
cl_ring_element R>uminus (const cl_ring_element& x)
cl_ring_element R>one ()
cl_ring_element R>canonhom (const cl_I& x)
cl_ring_element R>mul (const cl_ring_element& x, const cl_ring_element& y)
cl_ring_element R>square (const cl_ring_element& x)
cl_ring_element R>expt_pos (const cl_ring_element& x, const cl_I& y)
The following rings are builtin.
cl_null_ring cl_0_ring
The null ring, containing only zero.
cl_complex_ring cl_C_ring
The ring of complex numbers. This corresponds to the type cl_N
.
cl_real_ring cl_R_ring
The ring of real numbers. This corresponds to the type cl_R
.
cl_rational_ring cl_RA_ring
The ring of rational numbers. This corresponds to the type cl_RA
.
cl_integer_ring cl_I_ring
The ring of integers. This corresponds to the type cl_I
.
Type tests can be performed for any of cl_C_ring
, cl_R_ring
,
cl_RA_ring
, cl_I_ring
:
bool instanceof (const cl_number& x, const cl_number_ring& R)
Tests whether the given number is an element of the number ring R.
Next: Symbolic data types, Previous: Rings, Up: Top [Index]
• Modular integer rings:  
• Functions on modular integers: 
Next: Functions on modular integers, Up: Modular integers [Index]
CLN implements modular integers, i.e. integers modulo a fixed integer N.
The modulus is explicitly part of every modular integer. CLN doesn’t
allow you to (accidentally) mix elements of different modular rings,
e.g. (3 mod 4) + (2 mod 5)
will result in a runtime error.
(Ideally one would imagine a generic data type cl_MI(N)
, but C++
doesn’t have generic types. So one has to live with runtime checks.)
The class of modular integer rings is
Ring cl_ring <cln/ring.h>   Modular integer ring cl_modint_ring <cln/modinteger.h>
and the class of all modular integers (elements of modular integer rings) is
Modular integer cl_MI <cln/modinteger.h>
Modular integer rings are constructed using the function
cl_modint_ring find_modint_ring (const cl_I& N)
This function returns the modular ring ‘Z/NZ’. It takes care
of finding out about special cases of N
, like powers of two
and odd numbers for which Montgomery multiplication will be a win,
and precomputes any necessary auxiliary data for computing modulo N
.
There is a cache table of rings, indexed by N
(or, more precisely,
by abs(N)
). This ensures that the precomputation costs are reduced
to a minimum.
Modular integer rings can be compared for equality:
bool operator== (const cl_modint_ring&, const cl_modint_ring&)
bool operator!= (const cl_modint_ring&, const cl_modint_ring&)
These compare two modular integer rings for equality. Two different calls
to find_modint_ring
with the same argument necessarily return the
same ring because it is memoized in the cache table.
Previous: Modular integer rings, Up: Modular integers [Index]
Given a modular integer ring R
, the following members can be used.
cl_I R>modulus
This is the ring’s modulus, normalized to be nonnegative: abs(N)
.
cl_MI R>zero()
This returns 0 mod N
.
cl_MI R>one()
This returns 1 mod N
.
cl_MI R>canonhom (const cl_I& x)
This returns x mod N
.
cl_I R>retract (const cl_MI& x)
This is a partial inverse function to R>canonhom
. It returns the
standard representative (>=0
, <N
) of x
.
cl_MI R>random(random_state& randomstate)
cl_MI R>random()
This returns a random integer modulo N
.
The following operations are defined on modular integers.
cl_modint_ring x.ring ()
Returns the ring to which the modular integer x
belongs.
cl_MI operator+ (const cl_MI&, const cl_MI&)
Returns the sum of two modular integers. One of the arguments may also be a plain integer.
cl_MI operator (const cl_MI&, const cl_MI&)
Returns the difference of two modular integers. One of the arguments may also be a plain integer.
cl_MI operator (const cl_MI&)
Returns the negative of a modular integer.
cl_MI operator* (const cl_MI&, const cl_MI&)
Returns the product of two modular integers. One of the arguments may also be a plain integer.
cl_MI square (const cl_MI&)
Returns the square of a modular integer.
cl_MI recip (const cl_MI& x)
Returns the reciprocal x^1
of a modular integer x
. x
must be coprime to the modulus, otherwise an error message is issued.
cl_MI div (const cl_MI& x, const cl_MI& y)
Returns the quotient x*y^1
of two modular integers x
, y
.
y
must be coprime to the modulus, otherwise an error message is issued.
cl_MI expt_pos (const cl_MI& x, const cl_I& y)
y
must be > 0. Returns x^y
.
cl_MI expt (const cl_MI& x, const cl_I& y)
Returns x^y
. If y
is negative, x
must be coprime to the
modulus, else an error message is issued.
cl_MI operator<< (const cl_MI& x, const cl_I& y)
Returns x*2^y
.
cl_MI operator>> (const cl_MI& x, const cl_I& y)
Returns x*2^y
. When y
is positive, the modulus must be odd,
or an error message is issued.
bool operator== (const cl_MI&, const cl_MI&)
bool operator!= (const cl_MI&, const cl_MI&)
Compares two modular integers, belonging to the same modular integer ring, for equality.
bool zerop (const cl_MI& x)
Returns true if x
is 0 mod N
.
The following output functions are defined (see also the chapter on input/output).
void fprint (std::ostream& stream, const cl_MI& x)
std::ostream& operator<< (std::ostream& stream, const cl_MI& x)
Prints the modular integer x
on the stream
. The output may depend
on the global printer settings in the variable default_print_flags
.
Next: Univariate polynomials, Previous: Modular integers, Up: Top [Index]
CLN implements two symbolic (nonnumeric) data types: strings and symbols.
• Strings:  
• Symbols: 
Next: Symbols, Up: Symbolic data types [Index]
The class
String cl_string <cln/string.h>
implements immutable strings.
Strings are constructed through the following constructors:
cl_string (const char * s)
Returns an immutable copy of the (zeroterminated) C string s
.
cl_string (const char * ptr, unsigned long len)
Returns an immutable copy of the len
characters at
ptr[0]
, …, ptr[len1]
. NUL characters are allowed.
The following functions are available on strings:
operator =
Assignment from cl_string
and const char *
.
s.size()
strlen(s)
Returns the length of the string s
.
s[i]
Returns the i
th character of the string s
.
i
must be in the range 0 <= i < s.size()
.
bool equal (const cl_string& s1, const cl_string& s2)
Compares two strings for equality. One of the arguments may also be a
plain const char *
.
Previous: Strings, Up: Symbolic data types [Index]
Symbols are uniquified strings: all symbols with the same name are shared. This means that comparison of two symbols is fast (effectively just a pointer comparison), whereas comparison of two strings must in the worst case walk both strings until their end. Symbols are used, for example, as tags for properties, as names of variables in polynomial rings, etc.
Symbols are constructed through the following constructor:
cl_symbol (const cl_string& s)
Looks up or creates a new symbol with a given name.
The following operations are available on symbols:
cl_string (const cl_symbol& sym)
Conversion to cl_string
: Returns the string which names the symbol
sym
.
bool equal (const cl_symbol& sym1, const cl_symbol& sym2)
Compares two symbols for equality. This is very fast.
Next: Internals, Previous: Symbolic data types, Up: Top [Index]
• Univariate polynomial rings:  
• Functions on univariate polynomials:  
• Special polynomials: 
CLN implements univariate polynomials (polynomials in one variable) over an
arbitrary ring. The indeterminate variable may be either unnamed (and will be
printed according to default_print_flags.univpoly_varname
, which
defaults to ‘x’) or carry a given name. The base ring and the
indeterminate are explicitly part of every polynomial. CLN doesn’t allow you to
(accidentally) mix elements of different polynomial rings, e.g.
(a^2+1) * (b^31)
will result in a runtime error. (Ideally this should
return a multivariate polynomial, but they are not yet implemented in CLN.)
The classes of univariate polynomial rings are
Ring cl_ring <cln/ring.h>   Univariate polynomial ring cl_univpoly_ring <cln/univpoly.h>  +++    Complex polynomial ring  Modular integer polynomial ring cl_univpoly_complex_ring  cl_univpoly_modint_ring <cln/univpoly_complex.h>  <cln/univpoly_modint.h>  ++   Real polynomial ring  cl_univpoly_real_ring  <cln/univpoly_real.h>   ++   Rational polynomial ring  cl_univpoly_rational_ring  <cln/univpoly_rational.h>   ++  Integer polynomial ring cl_univpoly_integer_ring <cln/univpoly_integer.h>
and the corresponding classes of univariate polynomials are
Univariate polynomial cl_UP <cln/univpoly.h>  +++    Complex polynomial  Modular integer polynomial cl_UP_N  cl_UP_MI <cln/univpoly_complex.h>  <cln/univpoly_modint.h>  ++   Real polynomial  cl_UP_R  <cln/univpoly_real.h>   ++   Rational polynomial  cl_UP_RA  <cln/univpoly_rational.h>   ++  Integer polynomial cl_UP_I <cln/univpoly_integer.h>
Univariate polynomial rings are constructed using the functions
cl_univpoly_ring find_univpoly_ring (const cl_ring& R)
cl_univpoly_ring find_univpoly_ring (const cl_ring& R, const cl_symbol& varname)
This function returns the polynomial ring ‘R[X]’, unnamed or named.
R
may be an arbitrary ring. This function takes care of finding out
about special cases of R
, such as the rings of complex numbers,
real numbers, rational numbers, integers, or modular integer rings.
There is a cache table of rings, indexed by R
and varname
.
This ensures that two calls of this function with the same arguments will
return the same polynomial ring.
cl_univpoly_complex_ring find_univpoly_ring (const cl_complex_ring& R)
cl_univpoly_complex_ring find_univpoly_ring (const cl_complex_ring& R, const cl_symbol& varname)
cl_univpoly_real_ring find_univpoly_ring (const cl_real_ring& R)
cl_univpoly_real_ring find_univpoly_ring (const cl_real_ring& R, const cl_symbol& varname)
cl_univpoly_rational_ring find_univpoly_ring (const cl_rational_ring& R)
cl_univpoly_rational_ring find_univpoly_ring (const cl_rational_ring& R, const cl_symbol& varname)
cl_univpoly_integer_ring find_univpoly_ring (const cl_integer_ring& R)
cl_univpoly_integer_ring find_univpoly_ring (const cl_integer_ring& R, const cl_symbol& varname)
cl_univpoly_modint_ring find_univpoly_ring (const cl_modint_ring& R)
cl_univpoly_modint_ring find_univpoly_ring (const cl_modint_ring& R, const cl_symbol& varname)
These functions are equivalent to the general find_univpoly_ring
,
only the return type is more specific, according to the base ring’s type.
Next: Special polynomials, Previous: Univariate polynomial rings, Up: Univariate polynomials [Index]
Given a univariate polynomial ring R
, the following members can be used.
cl_ring R>basering()
This returns the base ring, as passed to ‘find_univpoly_ring’.
cl_UP R>zero()
This returns 0 in R
, a polynomial of degree 1.
cl_UP R>one()
This returns 1 in R
, a polynomial of degree == 0.
cl_UP R>canonhom (const cl_I& x)
This returns x in R
, a polynomial of degree <= 0.
cl_UP R>monomial (const cl_ring_element& x, uintL e)
This returns a sparse polynomial: x * X^e
, where X
is the
indeterminate.
cl_UP R>create (sintL degree)
Creates a new polynomial with a given degree. The zero polynomial has degree
1
. After creating the polynomial, you should put in the coefficients,
using the set_coeff
member function, and then call the finalize
member function.
The following are the only destructive operations on univariate polynomials.
void set_coeff (cl_UP& x, uintL index, const cl_ring_element& y)
This changes the coefficient of X^index
in x
to be y
.
After changing a polynomial and before applying any "normal" operation on it,
you should call its finalize
member function.
void finalize (cl_UP& x)
This function marks the endpoint of destructive modifications of a polynomial. It normalizes the internal representation so that subsequent computations have less overhead. Doing normal computations on unnormalized polynomials may produce wrong results or crash the program.
The following operations are defined on univariate polynomials.
cl_univpoly_ring x.ring ()
Returns the ring to which the univariate polynomial x
belongs.
cl_UP operator+ (const cl_UP&, const cl_UP&)
Returns the sum of two univariate polynomials.
cl_UP operator (const cl_UP&, const cl_UP&)
Returns the difference of two univariate polynomials.
cl_UP operator (const cl_UP&)
Returns the negative of a univariate polynomial.
cl_UP operator* (const cl_UP&, const cl_UP&)
Returns the product of two univariate polynomials. One of the arguments may also be a plain integer or an element of the base ring.
cl_UP square (const cl_UP&)
Returns the square of a univariate polynomial.
cl_UP expt_pos (const cl_UP& x, const cl_I& y)
y
must be > 0. Returns x^y
.
bool operator== (const cl_UP&, const cl_UP&)
bool operator!= (const cl_UP&, const cl_UP&)
Compares two univariate polynomials, belonging to the same univariate polynomial ring, for equality.
bool zerop (const cl_UP& x)
Returns true if x
is 0 in R
.
sintL degree (const cl_UP& x)
Returns the degree of the polynomial. The zero polynomial has degree 1
.
sintL ldegree (const cl_UP& x)
Returns the low degree of the polynomial. This is the degree of the first
nonvanishing polynomial coefficient. The zero polynomial has ldegree 1
.
cl_ring_element coeff (const cl_UP& x, uintL index)
Returns the coefficient of X^index
in the polynomial x
.
cl_ring_element x (const cl_ring_element& y)
Evaluation: If x
is a polynomial and y
belongs to the base ring,
then ‘x(y)’ returns the value of the substitution of y
into
x
.
cl_UP deriv (const cl_UP& x)
Returns the derivative of the polynomial x
with respect to the
indeterminate X
.
The following output functions are defined (see also the chapter on input/output).
void fprint (std::ostream& stream, const cl_UP& x)
std::ostream& operator<< (std::ostream& stream, const cl_UP& x)
Prints the univariate polynomial x
on the stream
. The output may
depend on the global printer settings in the variable
default_print_flags
.
Previous: Functions on univariate polynomials, Up: Univariate polynomials [Index]
The following functions return special polynomials.
cl_UP_I tschebychev (sintL n)
Returns the nth Chebyshev polynomial (n >= 0).
cl_UP_I hermite (sintL n)
Returns the nth Hermite polynomial (n >= 0).
cl_UP_RA legendre (sintL n)
Returns the nth Legendre polynomial (n >= 0).
cl_UP_I laguerre (sintL n)
Returns the nth Laguerre polynomial (n >= 0).
Information how to derive the differential equation satisfied by each
of these polynomials from their definition can be found in the
doc/polynomial/
directory.
Next: Using the library, Previous: Univariate polynomials, Up: Top [Index]
• Why C++ ?:  
• Memory efficiency:  
• Speed efficiency:  
• Garbage collection: 
Next: Memory efficiency, Up: Internals [Index]
Using C++ as an implementation language provides
operator+ (const cl_MI&, const cl_MI&)
requires that both
arguments belong to the same modular ring cannot be expressed as a compiletime
information.
+
, 
, *
,
=
, ==
, ... can be used in infix notation, which is more
convenient than Lisp notation ‘(+ x y)’ or C notation ‘add(x,y,&z)’.
With these language features, there is no need for two separate languages, one for the implementation of the library and one in which the library’s users can program. This means that a prototype implementation of an algorithm can be integrated into the library immediately after it has been tested and debugged. No need to rewrite it in a lowlevel language after having prototyped in a highlevel language.
Next: Speed efficiency, Previous: Why C++ ?, Up: Internals [Index]
In order to save memory allocations, CLN implements:
x+0
returns x
without copying
it.
>= 2^29
,
< 2^29
don’t consume heap memory, unless they were explicitly allocated
on the heap.
Next: Garbage collection, Previous: Memory efficiency, Up: Internals [Index]
Speed efficiency is obtained by the combination of the following tricks and algorithms:
i386
, m68k
, sparc
, mips
, arm
).
O(N^2)
algorithm, the Karatsuba multiplication, which is an
algorithm.
Previous: Speed efficiency, Up: Internals [Index]
All the number classes are reference count classes: They only contain a pointer to an object in the heap. Upon construction, assignment and destruction of number objects, only the objects’ reference count are manipulated.
Memory occupied by number objects are automatically reclaimed as soon as their reference count drops to zero.
For number rings, another strategy is implemented: There is a cache of, for example, the modular integer rings. A modular integer ring is destroyed only if its reference count dropped to zero and the cache is about to be resized. The effect of this strategy is that recently used rings remain cached, whereas undue memory consumption through cached rings is avoided.
Next: Customizing, Previous: Internals, Up: Top [Index]
For the following discussion, we will assume that you have installed
the CLN source in $CLN_DIR
and built it in $CLN_TARGETDIR
.
For example, for me it’s CLN_DIR="$HOME/cln"
and
CLN_TARGETDIR="$HOME/cln/linuxelf"
. You might define these as
environment variables, or directly substitute the appropriate values.
• Compiler options:  
• Include files:  
• An Example:  
• Debugging support:  
• Reporting Problems: 
Next: Include files, Up: Using the library [Index]
Until you have installed CLN in a public place, the following options are needed:
When you compile CLN application code, add the flags
I$CLN_DIR/include I$CLN_TARGETDIR/include
to the C++ compiler’s command line (make
variable CFLAGS or CXXFLAGS).
When you link CLN application code to form an executable, add the flags
$CLN_TARGETDIR/src/libcln.a
to the C/C++ compiler’s command line (make
variable LIBS).
If you did a make install
, the include files are installed in a
public directory (normally /usr/local/include
), hence you don’t
need special flags for compiling. The library has been installed to a
public directory as well (normally /usr/local/lib
), hence when
linking a CLN application it is sufficient to give the flag lcln
.
To make the creation of software packages that use CLN easier, the
pkgconfig
utility can be used. CLN provides all the necessary
metainformation in a file called cln.pc
(installed in
/usr/local/lib/pkgconfig
by default). A program using CLN can
be compiled and linked using ^{1}
g++ `pkgconfig libs cln` `pkgconfig cflags cln` prog.cc o prog
Software using GNU autoconf can check for CLN with the
PKG_CHECK_MODULES
macro supplied with pkgconfig
.
PKG_CHECK_MODULES([CLN], [cln >= MINVERSION])
This will check for CLN version at least MINVERSION. If the required version was found, the variables CLN_CFLAGS and CLN_LIBS are set. Otherwise the configure script aborts. If this is not the desired behaviour, use the following code instead ^{2}
PKG_CHECK_MODULES([CLN], [cln >= MINVERSION], [], [AC_MSG_WARNING([No suitable version of CLN can be found])])
Next: An Example, Previous: Compiler options, Up: Using the library [Index]
Here is a summary of the include files and their contents.
<cln/object.h>
General definitions, reference counting, garbage collection.
<cln/number.h>
The class cl_number.
<cln/complex.h>
Functions for class cl_N, the complex numbers.
<cln/real.h>
Functions for class cl_R, the real numbers.
<cln/float.h>
Functions for class cl_F, the floats.
<cln/sfloat.h>
Functions for class cl_SF, the shortfloats.
<cln/ffloat.h>
Functions for class cl_FF, the singlefloats.
<cln/dfloat.h>
Functions for class cl_DF, the doublefloats.
<cln/lfloat.h>
Functions for class cl_LF, the longfloats.
<cln/rational.h>
Functions for class cl_RA, the rational numbers.
<cln/integer.h>
Functions for class cl_I, the integers.
<cln/io.h>
Input/Output.
<cln/complex_io.h>
Input/Output for class cl_N, the complex numbers.
<cln/real_io.h>
Input/Output for class cl_R, the real numbers.
<cln/float_io.h>
Input/Output for class cl_F, the floats.
<cln/sfloat_io.h>
Input/Output for class cl_SF, the shortfloats.
<cln/ffloat_io.h>
Input/Output for class cl_FF, the singlefloats.
<cln/dfloat_io.h>
Input/Output for class cl_DF, the doublefloats.
<cln/lfloat_io.h>
Input/Output for class cl_LF, the longfloats.
<cln/rational_io.h>
Input/Output for class cl_RA, the rational numbers.
<cln/integer_io.h>
Input/Output for class cl_I, the integers.
<cln/input.h>
Flags for customizing input operations.
<cln/output.h>
Flags for customizing output operations.
<cln/malloc.h>
malloc_hook
, free_hook
.
<cln/exception.h>
Exception base class.
<cln/condition.h>
Conditions.
<cln/string.h>
Strings.
<cln/symbol.h>
Symbols.
<cln/proplist.h>
Property lists.
<cln/ring.h>
General rings.
<cln/null_ring.h>
The null ring.
<cln/complex_ring.h>
The ring of complex numbers.
<cln/real_ring.h>
The ring of real numbers.
<cln/rational_ring.h>
The ring of rational numbers.
<cln/integer_ring.h>
The ring of integers.
<cln/numtheory.h>
Number threory functions.
<cln/modinteger.h>
Modular integers.
<cln/V.h>
Vectors.
<cln/GV.h>
General vectors.
<cln/GV_number.h>
General vectors over cl_number.
<cln/GV_complex.h>
General vectors over cl_N.
<cln/GV_real.h>
General vectors over cl_R.
<cln/GV_rational.h>
General vectors over cl_RA.
<cln/GV_integer.h>
General vectors over cl_I.
<cln/GV_modinteger.h>
General vectors of modular integers.
<cln/SV.h>
Simple vectors.
<cln/SV_number.h>
Simple vectors over cl_number.
<cln/SV_complex.h>
Simple vectors over cl_N.
<cln/SV_real.h>
Simple vectors over cl_R.
<cln/SV_rational.h>
Simple vectors over cl_RA.
<cln/SV_integer.h>
Simple vectors over cl_I.
<cln/SV_ringelt.h>
Simple vectors of general ring elements.
<cln/univpoly.h>
Univariate polynomials.
<cln/univpoly_integer.h>
Univariate polynomials over the integers.
<cln/univpoly_rational.h>
Univariate polynomials over the rational numbers.
<cln/univpoly_real.h>
Univariate polynomials over the real numbers.
<cln/univpoly_complex.h>
Univariate polynomials over the complex numbers.
<cln/univpoly_modint.h>
Univariate polynomials over modular integer rings.
<cln/timing.h>
Timing facilities.
<cln/cln.h>
Includes all of the above.
Next: Debugging support, Previous: Include files, Up: Using the library [Index]
A function which computes the nth Fibonacci number can be written as follows.
#include <cln/integer.h> #include <cln/real.h> using namespace cln; // Returns F_n, computed as the nearest integer to // ((1+sqrt(5))/2)^n/sqrt(5). Assume n>=0. const cl_I fibonacci (int n) { // Need a precision of ((1+sqrt(5))/2)^n. float_format_t prec = float_format((int)(0.208987641*n+5)); cl_R sqrt5 = sqrt(cl_float(5,prec)); cl_R phi = (1+sqrt5)/2; return round1( expt(phi,n)/sqrt5 ); }
Let’s explain what is going on in detail.
The include file <cln/integer.h>
is necessary because the type
cl_I
is used in the function, and the include file <cln/real.h>
is needed for the type cl_R
and the floating point number functions.
The order of the include files does not matter. In order not to write
out cln::
foo in this simple example we can safely import
the whole namespace cln
.
Then comes the function declaration. The argument is an int
, the
result an integer. The return type is defined as ‘const cl_I’, not
simply ‘cl_I’, because that allows the compiler to detect typos like
‘fibonacci(n) = 100’. It would be possible to declare the return
type as const cl_R
(real number) or even const cl_N
(complex
number). We use the most specialized possible return type because functions
which call ‘fibonacci’ will be able to profit from the compiler’s type
analysis: Adding two integers is slightly more efficient than adding the
same objects declared as complex numbers, because it needs less type
dispatch. Also, when linking to CLN as a nonshared library, this minimizes
the size of the resulting executable program.
The result will be computed as expt(phi,n)/sqrt(5), rounded to the nearest integer. In order to get a correct result, the absolute error should be less than 1/2, i.e. the relative error should be less than sqrt(5)/(2*expt(phi,n)). To this end, the first line computes a floating point precision for sqrt(5) and phi.
Then sqrt(5) is computed by first converting the integer 5 to a floating point number and than taking the square root. The converse, first taking the square root of 5, and then converting to the desired precision, would not work in CLN: The square root would be computed to a default precision (normally singlefloat precision), and the following conversion could not help about the lacking accuracy. This is because CLN is not a symbolic computer algebra system and does not represent sqrt(5) in a nonnumeric way.
The type cl_R
for sqrt5 and, in the following line, phi is the only
possible choice. You cannot write cl_F
because the C++ compiler can
only infer that cl_float(5,prec)
is a real number. You cannot write
cl_N
because a ‘round1’ does not exist for general complex
numbers.
When the function returns, all the local variables in the function are automatically reclaimed (garbage collected). Only the result survives and gets passed to the caller.
The file fibonacci.cc
in the subdirectory examples
contains this implementation together with an even faster algorithm.
Next: Reporting Problems, Previous: An Example, Up: Using the library [Index]
When debugging a CLN application with GNU gdb
, two facilities are
available from the library:
runtime_exception
is thrown. When an exception is cought, the stack
has already been unwound, so it is may not be possible to tell at which
point the exception was thrown. For debugging, it is best to set up a
catchpoint at the event of throwning a C++ exception:
(gdb) catch throw
When this catchpoint is hit, look at the stack’s backtrace:
(gdb) where
When control over the type of exception is required, it may be possible
to set a breakpoint at the g++
runtime library function
__raise_exception
. Refer to the documentation of GNU gdb
for details.
print
command doesn’t know about
CLN’s types and therefore prints mostly useless hexadecimal addresses.
CLN offers a function cl_print
, callable from the debugger,
for printing number objects. In order to get this function, you have
to define the macro ‘CL_DEBUG’ and then include all the header files
for which you want cl_print
debugging support. For example:
#define CL_DEBUG #include <cln/string.h>
Now, if you have in your program a variable cl_string s
, and
inspect it under gdb
, the output may look like this:
(gdb) print s $7 = {<cl_gcpointer> = { = {pointer = 0x8055b60, heappointer = 0x8055b60, word = 134568800}}, } (gdb) call cl_print(s) (cl_string) "" $8 = 134568800
Note that the output of cl_print
goes to the program’s error output,
not to gdb’s standard output.
Note, however, that the above facility does not work with all CLN types,
only with number objects and similar. Therefore CLN offers a member function
debug_print()
on all CLN types. The same macro ‘CL_DEBUG’
is needed for this member function to be implemented. Under gdb
,
you call it like this:
(gdb) print s $7 = {<cl_gcpointer> = { = {pointer = 0x8055b60, heappointer = 0x8055b60, word = 134568800}}, } (gdb) call s.debug_print() (cl_string) "" (gdb) define cprint >call ($1).debug_print() >end (gdb) cprint s (cl_string) ""
Unfortunately, this feature does not seem to work under all circumstances.
Previous: Debugging support, Up: Using the library [Index]
If you encounter any problem, please don’t hesitate to send a detailed
bugreport to the clnlist@ginac.de
mailing list. Please think
about your bug: consider including a short description of your operating
system and compilation environment with corresponding version numbers. A
description of your configuration options may also be helpful. Also, a
short test program together with the output you get and the output you
expect will help us to reproduce it quickly. Finally, do not forget to
report the version number of CLN.
Next: Index, Previous: Using the library, Up: Top [Index]
• Error handling:  
• Floatingpoint underflow:  
• Customizing I/O:  
• Customizing the memory allocator: 
Next: Floatingpoint underflow, Up: Customizing [Index]
CLN signals abnormal situations by throwning exceptions. All exceptions
thrown by the library are of type runtime_exception
or of a
derived type. Class cln::runtime_exception
in turn is derived
from the C++ standard library class std::runtime_error
and
inherits the .what()
member function that can be used to query
details about the cause of error.
The most important classes thrown by the library are
Exception base class runtime_exception <cln/exception.h>  +++   Malformed number input Floatingpoint error read_number_exception floating_poing_exception <cln/number_io.h> <cln/float.h>
CLN has many more exception classes that allow for more finegrained control but I refrain from documenting them all here. They are all declared in the public header files and they are all subclasses of the above exceptions, so catching those you are always on the safe side.
Next: Customizing I/O, Previous: Error handling, Up: Customizing [Index]
Floating point underflow denotes the situation when a floatingpoint
number is to be created which is so close to 0
that its exponent
is too low to be represented internally. By default, this causes the
exception floating_point_underflow_exception
(subclass of
floating_point_exception
) to be thrown. If you set the global
variable
bool cl_inhibit_floating_point_underflow
to true
, the exception will be inhibited, and a floatingpoint
zero will be generated instead. The default value of
cl_inhibit_floating_point_underflow
is false
.
Next: Customizing the memory allocator, Previous: Floatingpoint underflow, Up: Customizing [Index]
The output of the function fprint
may be customized by changing the
value of the global variable default_print_flags
.
Previous: Customizing I/O, Up: Customizing [Index]
Every memory allocation of CLN is done through the function pointer
malloc_hook
. Freeing of this memory is done through the function
pointer free_hook
. The default versions of these functions,
provided in the library, call malloc
and free
and check
the malloc
result against NULL
.
If you want to provide another memory allocator, you need to define
the variables malloc_hook
and free_hook
yourself,
like this:
#include <cln/malloc.h> namespace cln { void* (*malloc_hook) (size_t size) = …; void (*free_hook) (void* ptr) = …; }
The cl_malloc_hook
function must not return a NULL
pointer.
It is not possible to change the memory allocator at runtime, because it is already called at program startup by the constructors of some global variables.
Previous: Customizing, Up: Top [Index]
Jump to:  A B C D E F G H I J L M N O P R S T U X Z 

Jump to:  A B C D E F G H I J L M N O P R S T U X Z 

If you installed CLN to
nonstandard location prefix, you need to set the
PKG_CONFIG_PATH
environment variable to prefix/lib/pkgconfig
for this to work.
See the pkgconfig
documentation for more details.