[GiNaC-list] Simplification in GiNaC

Vladimir V. Kisil kisilv at maths.leeds.ac.uk
Sat Jan 7 11:53:12 CET 2017


	Avoiding discussion on correct transformations towards simpler
  expressions in general, here is an advise on your particular example.

  You can use susb method with wildcards to make manual transformation

   pow(X,1/2)*pow(Y,1/2) -> pow(X*Y,1/2)

  Also, with square roots it will be better to use possymbol instead of
  realsymbol whenever possible. This even can make the desired
  transformation automatically through the expand method. (the desired
  answer is not correct for arbitrary reals, indeed)

  Best wishes,
Vladimir V. Kisil                 http://www.maths.leeds.ac.uk/~kisilv/
  Book:     Geometry of Mobius Transformations     http://goo.gl/EaG2Vu
  Software: Geometry of cycles          http://moebinv.sourceforge.net/
>>>>> On Fri, 6 Jan 2017 21:52:32 +0500, abpetrov <abpetrov at ufacom.ru> said:

    ABP> Hello, I recently wrote a simple program to learn some
    ABP> calculations with GiNaC. This works, But I got some expression
    ABP> which automatically don't become simple.  The question is: What
    ABP> is the simplest way to get the expected answer - Ax here?

    ABP> Best regards Petrov A.B.
    ABP> --------------------------------------------------------------------
    ABP> Output for program:

    ABP> Starting: ./test2 sqrt(m*x^2*A)*sqrt(m^(-1)*A) *** Exited
    ABP> normally ***

    ABP> ------------------------------------------------------------------

    ABP> Program:

    ABP> #include <iostream> using namespace std;

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

    ABP> void calc_example(){ realsymbol A("A"),m("m"),x("x"); ex e =
    ABP> sqrt(A*m*pow(x,2))*sqrt(A/m); cout << e << endl; }

    ABP> int main(int argc, char** argv) { calc_example(); return 0; }

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