[GiNaC-devel] Function & Power patch

[Vladimir Kisil]

		Dear All,

		There are many functions (abs, Heaviside, exp) which possess
  some power-simplification rules. I propose a patch to power.cpp and
  function.pl which allows to defines such rules in a way similar to
  derivative rules of functions. With the help of this I slightly
  improve the definition of abs() and it work now in this way:

#include <ginac/ginac.h>
using namespace GiNaC;

int main(){
	realsymbol a("a"); 
	cout << pow(abs(a), 2) << endl;
		// -> a^2
	cout << pow(abs(a), 3) << endl;
		// -> abs(a)^3
	symbol r("r");
	cout << pow(abs(r), 2) << endl;
		// -> abs(r)^2
	cout << pow(abs(r), 3) << endl;
		// -> abs(r)^3
}

  i.e. pow(abs(a), 2*n) is simplified to pow(a, 2*n) for real a. I also
  delete a duplicated line from ginac.texi.

  If it will be useful to add a definition of Heaviside function to the
  GiNaC core, I can send a patch as well.

  Best wishes,  
  Vladimir
-- 
Vladimir V. Kisil     email: kisilv at maths.leeds.ac.uk
--                      www: http://maths.leeds.ac.uk/~kisilv/

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