Re: [GiNaC-list] issues with simplify_indexed()

17 May 2011

      Hi,

I modified your code to output more details (I split the problematic line into 
several pieces) as follows:

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

int main()
{
        symbol i_sym("i"), j_sym("j"), k_sym("k"), 
               l_sym("l"), m_sym("m"), n_sym("n");
        idx i(i_sym, 2), j(j_sym, 2), k(k_sym, 2), 
            l(l_sym, 2), m(m_sym, 2), n(n_sym, 2);

        symbol alpha_sym("\\alpha"), beta_sym("\\beta"), gamma_sym("\\gamma");
        idx Va(alpha_sym, 3), Vb(beta_sym, 3), Vg(gamma_sym, 3);

        symbol U("U"), v("v"), h("h");

        exvector IJKLMNVec;
        idx IJKLMNIA[] ={i, j, k, l, m, n};
        IJKLMNVec.assign (IJKLMNIA,IJKLMNIA+6);

        ex myEx1 = indexed(h, IJKLMNVec)*indexed(U, i, Va);
        cout << "myEx1: " << myEx1 << endl;
        ex myEx2 = myEx1*indexed(U, k, Vb)*indexed(U, m, Vg);
        cout << "myEx2: " << myEx2 << endl;
	ex myEx3 = myEx2*indexed(v, j, Va);
        cout << "myEx3: " << myEx3 << endl;
	ex myEx4 = myEx3*indexed(v, l, Vb);
        cout << "myEx4: " << myEx4 << endl;
 	ex myEx5 = myEx4*indexed(v, n, Vg);
 	cout << "myEx5: " << myEx5 << endl;

        cout << "myEx5.simpl: " << myEx5.simplify_indexed() << endl;

        return 0;
}

The output shows the "myEx5" line, but nothing more. So, the error is in 
"simplify_indexed". I'm no expert, but maybe this helps a little.

Regards,

Ulrich.

Nachricht von Sonntag 15 Mai 2011 22:38:07:
...
I've been trying to get a little program of mine to work and well it
just doesn't terminate. Somewhere it gets snagged in an infinite loop
in the library. I'm pretty sure this is a library bug and I've alerted
development but in the mean while has an one encountered this before?
Has any one figured out a work around? I've whittled my program down
to the smallest most simple component I could get to non terminate.
The code looks like this.
#include <iostream>
#include <ginac/ginac.h>
using namespace std;
using namespace GiNaC;
int main()
{
  symbol i_sym("i"), j_sym("j"), k_sym("k"), l_sym("l"), m_sym("m"),
n_sym("n");
  idx i(i_sym, 2), j(j_sym, 2), k(k_sym, 2), l(l_sym, 2), m(m_sym, 2),
n(n_sym, 2);
symbol alpha_sym("\\alpha"), beta_sym("\\beta"), gamma_sym("\\gamma");
  idx Va(alpha_sym, 3), Vb(beta_sym, 3), Vg(gamma_sym, 3);
symbol U("U"), v("v"), h("h");
exvector IJKLMNVec;
  idx IJKLMNIA[] ={i, j, k, l, m, n};
  IJKLMNVec.assign (IJKLMNIA,IJKLMNIA+6);
ex myEx = (indexed(h, IJKLMNVec)*indexed(U, i, Va)
         *indexed(U, k, Vb)*indexed(U, m, Vg)*indexed(v, j, Va)
  *indexed(v, l, Vb)*indexed(v, n, Vg)).simplify_indexed();
cout << myEx << endl;
return 0;
}
This code never makes it to the cout code. it get trapped in a loop
before then.
Any one seen this before?
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Re: [GiNaC-list] issues with simplify_indexed()

Ulrich Loup