Now, here is one important property of GiNaC that differentiates it from
other computer algebra programs you may have used: GiNaC does @emph{not} use
the names of symbols to tell them apart, but a (hidden) serial number that
-is unique for each newly created @code{symbol} object. In you want to use
+is unique for each newly created @code{symbol} object. If you want to use
one and the same symbol in different places in your program, you must only
create one @code{symbol} object and pass that around. If you create another
symbol, even if it has the same name, GiNaC will treat it as a different
@cindex @code{possymbol()}
Furthermore, it is also possible to declare a symbol as positive. This will,
for instance, enable the automatic simplification of @code{abs(x)} into
-@code{x}. This is done by declaying the symbol as @code{possymbol x("x");}.
+@code{x}. This is done by declaring the symbol as @code{possymbol x("x");}.
@node Numbers, Constants, Symbols, Basic concepts
@end example
Note that the variable @code{answer} is constructed here as an integer
-by @code{numeric}'s copy constructor but in an intermediate step it
+by @code{numeric}'s copy constructor, but in an intermediate step it
holds a rational number represented as integer numerator and integer
denominator. When multiplied by 10, the denominator becomes unity and
the result is automatically converted to a pure integer again.
@tab @dots{}equal to zero
@item @code{.is_positive()}
@tab @dots{}not complex and greater than 0
+@item @code{.is_negative()}
+@tab @dots{}not complex and smaller than 0
@item @code{.is_integer()}
@tab @dots{}a (non-complex) integer
@item @code{.is_pos_integer()}
@end multitable
@end cartouche
+@page
+
@subsection Numeric functions
The following functions can be applied to @code{numeric} objects and will be
The predefined known constants are:
@cartouche
-@multitable @columnfractions .14 .30 .56
+@multitable @columnfractions .14 .32 .54
@item @strong{Name} @tab @strong{Common Name} @tab @strong{Numerical Value (to 35 digits)}
@item @code{Pi}
@tab Archimedes' constant
evaluation, is also available as
@example
ex adaptivesimpson(const ex & x, const ex & a, const ex & b, const ex & f,
-const ex & error)
+ const ex & error)
@end example
This function will throw an exception if the maximum depth is exceeded. The
last parameter of the function is optional and defaults to the
that performs some more expensive operations:
-@itemize
+@itemize @bullet
@item it checks the consistency of free indices in sums in the same way
@code{get_free_indices()} does
@item it tries to give dummy indices that appear in different terms of a sum
the header file @file{flags.h}), corresponding to three categories of
expressions in GiNaC:
-@itemize
+@itemize @bullet
@item @code{return_types::commutative}: Commutates with everything. Most GiNaC
classes are of this kind.
@item @code{return_types::noncommutative}: Non-commutative, belonging to a
The value returned by the @code{return_type_tinfo()} method is valid only
when the return type of the expression is @code{noncommutative}. It is a
-value that is unique to the class of the object and usually one of the
-constants in @file{tinfos.h}, or derived therefrom.
+value that is unique to the class of the object, but may vary every time a
+GiNaC program is being run (it is dynamically assigned on start-up).
Here are a couple of examples:
functional is not cyclic in
@tex $D \ne 4$
@end tex
+@ifnottex
+@math{D != 4}
+@end ifnottex
dimensions when acting on
expressions containing @samp{gamma5}, so it's not a proper trace. This
-@samp{gamma5} scheme is described in greater detail in
-@cite{The Role of gamma5 in Dimensional Regularization}.
+@samp{gamma5} scheme is described in greater detail in the article
+@cite{The Role of gamma5 in Dimensional Regularization} (@ref{Bibliography}).
The value of the trace itself is also usually different in 4 and in
@tex $D \ne 4$
@end tex
+@ifnottex
+@math{D != 4}
+@end ifnottex
dimensions:
@example
@subsubsection A generic Clifford algebra
A generic Clifford algebra, i.e. a
-@tex
-$2^n$
+@tex $2^n$
@end tex
+@ifnottex
+2^n
+@end ifnottex
dimensional algebra with
generators
@tex $e_k$
@end tex
+@ifnottex
+e_k
+@end ifnottex
satisfying the identities
@tex
-$e_i e_j + e_j e_i = M(i, j) + M(j, i) $
+$e_i e_j + e_j e_i = M(i, j) + M(j, i)$
@end tex
@ifnottex
e~i e~j + e~j e~i = M(i, j) + M(j, i)
@code{\clifford[1]@{e@}^@{@{\nu@}@}}, where @code{1} is the
@code{representation_label} and @code{\nu} is the index of the
corresponding unit. This provides a flexible typesetting with a suitable
-defintion of the @code{\clifford} command. For example, the definition
+definition of the @code{\clifford} command. For example, the definition
@example
\newcommand@{\clifford@}[1][]@{@}
@end example
large @code{subs()} operations significantly faster if you are not using
patterns. The second option, @code{subs_options::algebraic} enables
algebraic substitutions in products and powers.
-@ref{Pattern matching and advanced substitutions}, for more information
+@xref{Pattern matching and advanced substitutions}, for more information
about patterns and algebraic substitutions. The third option,
@code{subs_options::no_index_renaming} disables the feature that dummy
-indices are renamed if the subsitution could give a result in which a
+indices are renamed if the substitution could give a result in which a
dummy index occurs more than two times. This is sometimes necessary if
you want to use @code{subs()} to rename your dummy indices.
Notes:
-@itemize
+@itemize @bullet
@item Wildcards behave like symbols and are subject to the same algebraic
rules. E.g., @samp{$0+2*$0} is automatically transformed to @samp{3*$0}.
@item As shown in the last example, to use wildcards for indices you have to
> match((a+b)*(a+c),($1+b)*($1+c));
@{$1==a@}
> match((a+b)*(a+c),(a+$1)*(a+$2));
-@{$1==c,$2==b@}
+@{$1==b,$2==c@}
(Unpredictable. The result might also be [$1==c,$2==b].)
> match((a+b)*(a+c),($1+$2)*($1+$3));
(The result is undefined. Due to the sequential nature of the algorithm
Both @code{has()} and @code{subs()} take an optional argument to pass them
extra options. This section describes what happens if you give the former
the option @code{has_options::algebraic} or the latter
-@code{subs:options::algebraic}. In that case the matching condition for
+@code{subs_options::algebraic}. In that case the matching condition for
powers and multiplications is changed in such a way that they become
more intuitive. Intuition says that @code{x*y} is a part of @code{x*y*z}.
If you use these options you will find that
@code{(x^5*y^2*z).subs(x^2*y^2==c, subs_options::algebraic)} will return
@code{x*c^2*z}. This also works with negative powers:
@code{(x^(-3)*y^(-2)*z).subs(1/(x*y)==c, subs_options::algebraic)} will
-return @code{x^(-1)*c^2*z}. Note that this only works for multiplications
+return @code{x^(-1)*c^2*z}.
+
+@strong{Note:} this only works for multiplications
and not for locating @code{x+y} within @code{x+y+z}.
@tex
$\pi$
@end tex
+@ifnottex
+@math{Pi}
+@end ifnottex
(for which there already exists the built-in constant @code{Pi})
using John Machin's amazing formula
@tex
@}
@end example
+@page
+
@node Built-in functions, Multiple polylogarithms, Symmetrization, Methods and functions
@c node-name, next, previous, up
@section Predefined mathematical functions
@tex
$\zeta(m_1,m_2,\ldots,m_k)$.
@end tex
+@ifnottex
+@command{\mbox@{Li@}_@{m_1,m_2,...,m_k@}(x_1,x_2,...,x_k)},
+@command{\mbox@{S@}_@{n,p@}(x)},
+@command{\mbox@{H@}_@{m_1,m_2,...,m_k@}(x)} and
+@command{\zeta(m_1,m_2,...,m_k)} (with the dots replaced by actual parameters).
+@end ifnottex
If @code{zeta} is an alternating zeta sum, i.e. @code{zeta(m,s)}, the indices with negative sign
are printed with a line above, e.g.
@tex
$\zeta(5,\overline{2})$.
@end tex
+@ifnottex
+@command{\zeta(5,\overline@{2@})}.
+@end ifnottex
The order of indices and arguments in the GiNaC @code{lst}s and in the output is the same.
Definitions and analytical as well as numerical properties of multiple polylogarithms
@tex
$\zeta(1,2)$ evaluates to infinity.
@end tex
-So in comparison to the referenced publications the order of indices and arguments for @code{Li}
-is reversed.
+@ifnottex
+@code{Li_@{m_1,m_2,m_3@}(x,1,1) = H_@{m_1,m_2,m_3@}(x)} and
+@code{Li_@{2,1@}(1,1) = zeta(2,1) = zeta(3)}, but
+@code{zeta(1,2)} evaluates to infinity.
+@end ifnottex
+So in comparison to the older ones of the referenced publications the order of
+indices and arguments for @code{Li} is reversed.
The functions only evaluate if the indices are integers greater than zero, except for the indices
@code{s} in @code{zeta} and @code{G} as well as @code{m} in @code{H}. Since @code{s}
@tex
$\zeta(\overline{3},4)$
@end tex
+@ifnottex
+@command{zeta(\overline@{3@},4)}
+@end ifnottex
and
@code{G(lst(a,b), lst(-1,1), c)} means
@tex
$G(a-0\epsilon,b+0\epsilon;c)$.
@end tex
+@ifnottex
+@command{G(a-0\epsilon,b+0\epsilon;c)}.
+@end ifnottex
The definition of @code{H} allows indices to be 0, 1 or -1 (in expanded notation) or equally to
be any integer (in compact notation). With GiNaC expanded and compact notation can be mixed,
e.g. @code{lst(0,0,-1,0,1,0,0)}, @code{lst(0,0,-1,2,0,0)} and @code{lst(-3,2,0,0)} are equivalent as
@tex
$\zeta(1)$.
@end tex
+@ifnottex
+@command{zeta(1)}.
+@end ifnottex
In long expressions this helps a lot with debugging, because you can easily spot
the divergencies. But on the other hand, you have to make sure for yourself, that no illegal
cancellations of divergencies happen.
that return respectively the complex conjugate, the real part and the
imaginary part of an expression. Complex conjugation works as expected
-for all built-in functinos and objects. Taking real and imaginary
+for all built-in functions and objects. Taking real and imaginary
parts has not yet been implemented for all built-in functions. In cases where
it is not known how to conjugate or take a real/imaginary part one
of the functions @code{conjugate}, @code{real_part} or @code{imag_part}
GINAC_DECLARE_REGISTERED_CLASS(mystring, basic)
public:
- mystring(const string &s);
- mystring(const char *s);
+ mystring(const string & s);
+ mystring(const char * s);
private:
string str;
@code{mystring()}, the default constructor.
@item
-@code{void archive(archive_node &n)}, the archiving function. This stores all
+@code{void archive(archive_node & n)}, the archiving function. This stores all
information needed to reconstruct an object of this class inside an
@code{archive_node}.
@item
-@code{mystring(const archive_node &n, lst &sym_lst)}, the unarchiving
+@code{mystring(const archive_node & n, lst & sym_lst)}, the unarchiving
constructor. This constructs an instance of the class from the information
found in an @code{archive_node}.
@item
-@code{ex unarchive(const archive_node &n, lst &sym_lst)}, the static
+@code{ex unarchive(const archive_node & n, lst & sym_lst)}, the static
unarchiving function. It constructs a new instance by calling the unarchiving
constructor.
@item
@cindex @code{compare_same_type()}
-@code{int compare_same_type(const basic &other)}, which is used internally
+@code{int compare_same_type(const basic & other)}, which is used internally
by GiNaC to establish a canonical sort order for terms. It returns 0, +1 or
-1, depending on the relative order of this object and the @code{other}
object. If it returns 0, the objects are considered equal.
defined.
@item
-And, of course, @code{mystring(const string &s)} and @code{mystring(const char *s)}
+And, of course, @code{mystring(const string & s)} and @code{mystring(const char * s)}
which are the two constructors we declared.
@end itemize
is really simple. First, the archiving function:
@example
-void mystring::archive(archive_node &n) const
+void mystring::archive(archive_node & n) const
@{
inherited::archive(n);
n.add_string("string", str);
function:
@example
-mystring::mystring(const archive_node &n, lst &sym_lst) : inherited(n, sym_lst)
+mystring::mystring(const archive_node & n, lst & sym_lst) : inherited(n, sym_lst)
@{
n.find_string("string", str);
@}
Finally, the unarchiving function:
@example
-ex mystring::unarchive(const archive_node &n, lst &sym_lst)
+ex mystring::unarchive(const archive_node & n, lst & sym_lst)
@{
return (new mystring(n, sym_lst))->setflag(status_flags::dynallocated);
@}
the string members:
@example
-int mystring::compare_same_type(const basic &other) const
+int mystring::compare_same_type(const basic & other) const
@{
const mystring &o = static_cast<const mystring &>(other);
int cmpval = str.compare(o.str);
Now the only thing missing is our two new constructors:
@example
-mystring::mystring(const string &s) : inherited(&mystring::tinfo_static), str(s) @{@}
-mystring::mystring(const char *s) : inherited(&mystring::tinfo_static), str(s) @{@}
+mystring::mystring(const string & s)
+ : inherited(&mystring::tinfo_static), str(s) @{@}
+mystring::mystring(const char * s)
+ : inherited(&mystring::tinfo_static), str(s) @{@}
@end example
No surprises here. We set the @code{str} member from the argument and
@{
...
protected:
- void do_print(const print_context &c, unsigned level = 0) const;
+ void do_print(const print_context & c, unsigned level = 0) const;
...
@};
-void mystring::do_print(const print_context &c, unsigned level) const
+void mystring::do_print(const print_context & c, unsigned level) const
@{
// print_context::s is a reference to an ostream
c.s << '\"' << str << '\"';
@cindex @code{is_equal_same_type()}
@example
unsigned calchash() const;
-bool is_equal_same_type(const basic &other) const;
+bool is_equal_same_type(const basic & other) const;
@end example
The @code{calchash()} method returns an @code{unsigned} hash value for the
git://www.ginac.de / ginac.git / blobdiff