From 778927a23b7807cb9809047211265000650eda56 Mon Sep 17 00:00:00 2001 From: Christian Bauer Date: Thu, 21 Nov 2002 22:56:49 +0000 Subject: [PATCH] documentation update --- NEWS | 2 ++ doc/tutorial/ginac.texi | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/NEWS b/NEWS index 81f2975f..c25a0867 100644 --- a/NEWS +++ b/NEWS @@ -10,6 +10,8 @@ This file records noteworthy changes. LaTeX output. * Added symbolic_matrix() for the convenient creation of matrices filled with symbols. +* Added collect_common_factors() which collects common factors from the + terms of sums. 1.0.12 (30 October 2002) * Fixed a bug in power::expand() that could produce invalid expressions. diff --git a/doc/tutorial/ginac.texi b/doc/tutorial/ginac.texi index 98033e40..54414c91 100644 --- a/doc/tutorial/ginac.texi +++ b/doc/tutorial/ginac.texi @@ -3405,6 +3405,7 @@ argument. You can not use functions like @samp{diff()}, @samp{op()}, @subsection Expanding and collecting @cindex @code{expand()} @cindex @code{collect()} +@cindex @code{collect_common_factors()} A polynomial in one or more variables has many equivalent representations. Some useful ones serve a specific purpose. Consider @@ -3463,6 +3464,25 @@ d*sin(x)+(d*sin(x)+sin(y)+d*sin(y)+sin(x))*p+(d*sin(x)+sin(y)+d*sin(y)+sin(x))*q (1+q+d*(1+q+p)+p)*sin(y)+(1+q+d*(1+q+p)+p)*sin(x) @end example +Polynomials can often be brought into a more compact form by collecting +common factors from the terms of sums. This is accomplished by the function + +@example +ex collect_common_factors(const ex & e); +@end example + +This function doesn't perform a full factorization but only looks for +factors which are already explicitly present: + +@example +> collect_common_factors(a*x+a*y); +(x+y)*a +> collect_common_factors(a*x^2+2*a*x*y+a*y^2); +a*(2*x*y+y^2+x^2) +> collect_common_factors(a*(b*(a+c)*x+b*((a+c)*x+(a+c)*y)*y)); +(c+a)*a*(x*y+y^2+x)*b +@end example + @subsection Degree and coefficients @cindex @code{degree()} @cindex @code{ldegree()} -- 2.37.1