infinite loop on gcd() probably just a long time. Workaround exists

My suspicion is that you are just not waiting long enough for the
subresultant gcd to finish.  if you do gcd:spmod; then the answer
returns almost instantly that gcd=1. This uses a different gcd
program that is more efficient on sparse polynomials.

I set the subres gcd running on (commercial) macsyma and it is going
for minutes, so far.




For purposes of people who might want to try this, I have reformatted
your input so it does not break symbols over lines.
also, the fullratsimp is unnecessary, since the gcd() command converts
its inputs to fully-expanded form.

 (f1:w1, f2:w5-w3, f3:w1*w5-w2*w4+w1*w3,
f4:w1^2*w5-w1*w2*w4+w2^2*w3-2*w1^2*w3,
f5:w2^2*w5-w1^2*w5-w1*w2*w4-w2^2*w3+2*w1^2*w3,
g1:p6*w1*w2*w5^3-p7*w1^2*w5^3-p6*w2^2*w4*w5^2+
2*p7*w1*w2*w4*w5^2-p6*w1^2*w4*w5^2+
p4*w1*w2*w3*w5^2+p7*w1^2*w3*w5^2-
pE*w1*w2^2*w5^2-pD*w1^2*w2*w5^2+
pE*w1^3*w5^2-p7*w2^2*w4^2*w5-p4*w1*w2*w4^2*w5+
p6*w2^2*w3*w4*w5-2*p4*w2^2*w3*w4*w5-
3*p7*w1*w2*w3*w4*w5+p6*w1^2*w3*w4*w5+
p4*w1^2*w3*w4*w5+pE*w2^3*w4*w5+
2*pD*w1*w2^2*w4*w5+pC*w1^2*w2*w4*w5-
p6*w1*w2*w3^2*w5+p4*w1*w2*w3^2*w5+2*p7*w1^2*w3^2*w5-
pD*w1^2*w2*w3*w5-pE*w1^3*w3*w5-
pC*w1^3*w3*w5+p6*w2^2*w4^3+
p4*w2^2*w4^3+2*p7*w2^2*w3*w4^2-
2*p6*w1*w2*w3*w4^2+p2*w1*w2*w3*w4^2-
pD*w2^3*w4^2-pE*w1*w2^2*w4^2-
pC*w1*w2^2*w4^2-p6*w2^2*w3^2*w4+
p4*w2^2*w3^2*w4-p2*w2^2*w3^2*w4-
p7*w1*w2*w3^2*w4+p1*w1*w2*w3^2*w4+
p6*w1^2*w3^2*w4-p4*w1^2*w3^2*w4-
p2*w1^2*w3^2*w4-pE*w2^3*w3*w4+
pC*w2^3*w3*w4+pD*w1*w2^2*w3*w4+
2*pE*w1^2*w2*w3*w4-pA*w1^2*w2*w3*w4+
p6*w1*w2*w3^3-p4*w1*w2*w3^3+
p2*w1*w2*w3^3-p7*w1^2*w3^3-
p1*w1^2*w3^3+pE*w1*w2^2*w3^2-
pC*w1*w2^2*w3^2-pE*w1^3*w3^2+
pC*w1^3*w3^2+pA*w1^3*w3^2);
.......

>gcd(g1,fullratsimp(f2*f3*f4*f5));
>:lisp (room)
>
>The last gcd call has an infinite loop.
>
>I will tries to find a smaller g1 expression if I can in the first step.
>If I can't, maybe I will write a "random polynomials generator"
>
>Laurent
>
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