[GiNaC-list] normal() bug-or-feature

[Christian Bauer]

Hi!

On Tue, Nov 09, 2004 at 10:10:07PM +0300, Sheplyakov Alexei wrote:
> 	symbol m1("m1");
> 	symbol m2("m2");
> 	symbol x("x");
> 	ex e1 = pow(x,2)*pow(m1,2) - pow(x,2)*pow(m2,2);
> 	ex e2 = pow(pow(x,2)*pow(m1,2)-pow(x,2)*pow(m2,2),100);
> 	ex ca, cb, gc;
> 	gc = gcd(e1, e2, &ca, &cb, false);
> 	cout << c2 << endl;
> 	// this won't be just x^198*(m1^2-m2^2)^99.
> 	// (m1^2-m2^2)^99 gets expanded.
> 	cout << (e1/e2).normal() << endl;
> 	// won't print just x^(-198)*(m1^2-m2^2)^(-99), 
> 	// (m1^2-m2^2)^99 gets expanded 

Hm, which version of GiNaC are you using? I'm getting ca = 1,
cb = (-m2^2*x^2+m1^2*x^2)^99, and e1/e2 gets simplified to
(-m2^2*x^2+m1^2*x^2)^(-99) by power::eval() even before normal()
is invoked. Besides, gcd() already has heuristics for the cases
b==a^n (or a==b^n).

Bye,
Christian

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