Replaced GiNaC Group names by web address.

[ginac.git] / doc / tutorial / ginac.texi

diff --git a/doc/tutorial/ginac.texi b/doc/tutorial/ginac.texi
index 76c207426f9d75300369945dccce2f1e0f2baff4..d0b12a76817146ae518f6ff5f325241bc4f0066d 100644 (file)
--- a/doc/tutorial/ginac.texi
+++ b/doc/tutorial/ginac.texi
@@ -47,8 +47,7 @@ notice identical to this one.
 @title GiNaC @value{VERSION}
 @subtitle An open framework for symbolic computation within the C++ programming language
 @subtitle @value{UPDATED}
-@author The GiNaC Group:
-@author Christian Bauer, Alexander Frink, Richard Kreckel, Jens Vollinga
+@author @uref{http://www.ginac.de}
 
 @page
 @vskip 0pt plus 1filll
@@ -1155,11 +1154,17 @@ in the complex domain.  As a consequence, operations like complex conjugation,
 for example (@pxref{Complex expressions}), do @emph{not} evaluate if applied
 to such symbols. Likewise @code{log(exp(x))} does not evaluate to @code{x},
 because of the unknown imaginary part of @code{x}.
-On the other hand, if you are sure that your symbols will hold only real values, you
-would like to have such functions evaluated. Therefore GiNaC allows you to specify
+On the other hand, if you are sure that your symbols will hold only real
+values, you would like to have such functions evaluated. Therefore GiNaC
+allows you to specify
 the domain of the symbol. Instead of @code{symbol x("x");} you can write
 @code{realsymbol x("x");} to tell GiNaC that @code{x} stands in for real values.
 
+@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");}.
+
 
 @node Numbers, Constants, Symbols, Basic concepts
 @c    node-name, next, previous, up
@@ -2723,11 +2728,7 @@ arithmetic class, you just pass it to @code{simplify_indexed()}):
 The @code{scalar_products} object @code{sp} acts as a storage for the
 scalar products added to it with the @code{.add()} method. This method
 takes three arguments: the two expressions of which the scalar product is
-taken, and the expression to replace it with. After @code{sp.add(A, B, 0)},
-@code{simplify_indexed()} will replace all scalar products of indexed
-objects that have the symbols @code{A} and @code{B} as base expressions
-with the single value 0. The number, type and dimension of the indices
-don't matter; @samp{A~mu~nu*B.mu.nu} would also be replaced by 0.
+taken, and the expression to replace it with.
 
 @cindex @code{expand()}
 The example above also illustrates a feature of the @code{expand()} method:
@@ -3307,7 +3308,11 @@ generators, an index @code{mu} with a numeric value may be of type
 @code{idx} as well.
 Parameter @code{metr} defines the metric @math{M(i, j)} and can be
 represented by a square @code{matrix}, @code{tensormetric} or @code{indexed} class
-object. Optional parameter @code{rl} allows to distinguish different
+object. In fact, any expression either with two free indices or without
+indices at all is admitted as @code{metr}. In the later case an @code{indexed}
+object with two newly created indices with @code{metr} as its
+@code{op(0)} will be used.
+Optional parameter @code{rl} allows to distinguish different
 Clifford algebras, which will commute with each other. The last
 optional parameter @code{anticommuting} defines if the anticommuting
 assumption (i.e.