Expand does not expands?
zellerin at winbase.software602.cz
zellerin at winbase.software602.cz
Mon May 28 13:51:51 CEST 2001
Hello,
I got to GiNaC only recently, and I have some troubles with the expand()
function. I would expect following code

#include <ginac/ginac.h>
using namespace GiNaC;
symbol x("x"), y("y");
ex laplace_in_oblates(const ex& potential)
{
ex x_part=diff((x*x1)*diff(potential,x), x);
ex y_part=diff((1y*y)*diff(potential,y), y);
return normal(x_part+y_part);
}
int main()
{
ex R=sqrt(x*x+y*y1);
ex tmp=expand(pow(R, 5)*laplace_in_oblates(1/R));
cout << tmp<<" = "<<tmp.normal() << endl;
return 0;
}

to yield 0 = 0, but it gives
3*(1+x^2+y^2)*y^23*x^2+3*x^43*(1+x^2+y^2)*x^23*y^4+3*y^2 = 0
I would say that the polynomial on the left side is not expanded, in spite of
the fact that it should be result of an expand. Anyone give me a hint what I
am doing/expecting wrong?
(tried on GiNaC version 0.6.4 on RedHat Linux 6.1 and GiNaC 0.8.3 on RH 7.1)
Thanks
Tomas Zellerin

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