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Topic review - Bug in minAssGTZ with real coefficients?
Author Message
  Post subject:  Re: Bug in minAssGTZ with real coefficients?  Reply with quote
main incredience of minAssGTZ are Groebner bases,
which are not useful for inexact coeffcients, and factorization,
which is not implemented for inexact coeffcients:
in short: that cannot work.
Post Posted: Sat Aug 25, 2018 4:52 pm
  Post subject:  Bug in minAssGTZ with real coefficients?  Reply with quote
Hi all,

The following program causes Singular to receive a segmentation fault and exit.

(background: if you replace the coefficient ring to Q, the program works, but is very slow: the std in the beginning takes about an hour. I guessed that the reason was the appearnace of very large coefficients and tried to switch to real coefficients. It really made the program faster, but...)

Thanks,

ring R=(real,200),(a,b,c,d,e,f),dp;
poly pxb=a+b*d-a*b*d+c*e-a*c*e-b*c*d*e+a*b*c*d*e+c*d*f-a*c*d*f-b*c*d*f+a*b*c*d*f+b*e*f-a*b*e*f-b*c*e*f+a*b*c*e*f-b*d*e*f+a*b*d*e*f-c*d*e*f+a*c*d*e*f+2b*c*d*e*f-2a*b*c*d*e*f;
poly pxA=a+b-a*b+c-a*c-b*c+a*b*c;
poly pab=a*b+d-a*b*d+b*c*e-a*b*c*e-b*c*d*e+a*b*c*d*e+a*c*f-a*b*c*f-a*c*d*f+a*b*c*d*f+e*f-a*b*e*f-a*c*e*f-b*c*e*f+2a*b*c*e*f-d*e*f+a*b*d*e*f+a*c*d*e*f+b*c*d*e*f-2a*b*c*d*e*f;
poly pa2b=a*c+b*c*d-a*b*c*d+e-a*c*e-b*c*d*e+a*b*c*d*e+a*b*f-a*b*c*f+d*f-a*b*d*f-a*c*d*f-b*c*d*f+2a*b*c*d*f-a*b*e*f+a*b*c*e*f-d*e*f+a*b*d*e*f+a*c*d*e*f+b*c*d*e*f-2a*b*c*d*e*f;
poly dpxb0=1-b*d-c*e+b*c*d*e-c*d*f+b*c*d*f-b*e*f+b*c*e*f+b*d*e*f+c*d*e*f-2b*c*d*e*f;
poly dpxA0=1-b-c+b*c;
poly dpab0=b-b*d-b*c*e+b*c*d*e+c*f-b*c*f-c*d*f+b*c*d*f-b*e*f-c*e*f+2b*c*e*f+b*d*e*f+c*d*e*f-2b*c*d*e*f;
poly dpxb1=d-a*d-c*d*e+a*c*d*e-c*d*f+a*c*d*f+e*f-a*e*f-c*e*f+a*c*e*f-d*e*f+a*d*e*f+2c*d*e*f-2a*c*d*e*f;
poly dpxA1=1-a-c+a*c;
poly dpab1=a-a*d+c*e-a*c*e-c*d*e+a*c*d*e-a*c*f+a*c*d*f-a*e*f-c*e*f+2a*c*e*f+a*d*e*f+c*d*e*f-2a*c*d*e*f;
poly dpxb2=e-a*e-b*d*e+a*b*d*e+d*f-a*d*f-b*d*f+a*b*d*f-b*e*f+a*b*e*f-d*e*f+a*d*e*f+2b*d*e*f-2a*b*d*e*f;
poly dpxA2=1-a-b+a*b;
poly dpab2=b*e-a*b*e-b*d*e+a*b*d*e+a*f-a*b*f-a*d*f+a*b*d*f-a*e*f-b*e*f+2a*b*e*f+a*d*e*f+b*d*e*f-2a*b*d*e*f;
poly dpxb3=b-a*b-b*c*e+a*b*c*e+c*f-a*c*f-b*c*f+a*b*c*f-b*e*f+a*b*e*f-c*e*f+a*c*e*f+2b*c*e*f-2a*b*c*e*f;
poly dpxA3=0;
poly dpab3=1-a*b-b*c*e+a*b*c*e-a*c*f+a*b*c*f-e*f+a*b*e*f+a*c*e*f+b*c*e*f-2a*b*c*e*f;
poly dpxb4=c-a*c-b*c*d+a*b*c*d+b*f-a*b*f-b*c*f+a*b*c*f-b*d*f+a*b*d*f-c*d*f+a*c*d*f+2b*c*d*f-2a*b*c*d*f;
poly dpxA4=0;
poly dpab4=b*c-a*b*c-b*c*d+a*b*c*d+f-a*b*f-a*c*f-b*c*f+2a*b*c*f-d*f+a*b*d*f+a*c*d*f+b*c*d*f-2a*b*c*d*f;
poly dpxb5=c*d-a*c*d-b*c*d+a*b*c*d+b*e-a*b*e-b*c*e+a*b*c*e-b*d*e+a*b*d*e-c*d*e+a*c*d*e+2b*c*d*e-2a*b*c*d*e;
poly dpxA5=0;
poly dpab5=a*c-a*b*c-a*c*d+a*b*c*d+e-a*b*e-a*c*e-b*c*e+2a*b*c*e-d*e+a*b*d*e+a*c*d*e+b*c*d*e-2a*b*c*d*e;
ideal I=pab-pa2b,dpxb0-pxA*dpab0-dpxA0*pab,dpxb1-pxA*dpab1-dpxA1*pab,dpxb2-pxA*dpab2-dpxA2*pab,dpxb3-pxA*dpab3-dpxA3*pab,dpxb4-pxA*dpab4-dpxA4*pab,dpxb5-pxA*dpab5-dpxA5*pab;
option(prot);
LIB "primdec.lib";
list l=minAssGTZ(I);
Post Posted: Fri Aug 17, 2018 7:29 pm


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