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Why the "resultant" command doesn't work in my code? https://www.singular.uni-kl.de/forum/viewtopic.php?f=10&t=2907 |
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Author: | Alb [ Thu Apr 16, 2020 8:31 am ] |
Post subject: | Why the "resultant" command doesn't work in my code? |
LIB "matrix.lib"; ring r=0,(s,t,u,x(0..5)),dp; varstr(r); ideal I=x(0)-s2,x(1)-t2,x(2)-u2,x(3)-st,x(4)-su,x(5)-tu; std(I); vector v=[x(3)*x(4)-x(0)*x(5),x(1)*x(4)-x(3)*x(5),x(2)*x(3)-x(4)*x(5),x(1 )*x(2)-x(5)^2,x(0)*x(2)-x(4)^2,x(0)*x(1)-x(3)^2]; matrix A[4][6]=1,1,1,1,1,0,0,0,0,0,1,2,2,2,1,1,1,0,0,0,-1,-2,1,0,1; print(A); matrix B=A*v; print(B); ideal F=flatten(B); print(F); ideal J=eliminate(F,x(4)*x(5)); print(J); poly f=J[1]; print(f); poly g=J[2]; print(g); poly h=resultant(f,g,x(3)); the resultat gives me 0. Instead if I change the ring and try it with the same polynomials as above, it works like this ring r=0, (x,y,z,w),dp; poly f=14xy2+xyz+14xyw-14xw2-zw2-14w3; poly g=4x2y+6xy2+xyz+10xyw-4xw2-6yw2-yw2-10w3; resultant(f,g,x); thank you in advance! |
Author: | hannes [ Thu Apr 16, 2020 12:05 pm ] |
Post subject: | Re: Why the "resultant" command doesn't work in my code? |
The results are correct (resultant is 0 in the first case). But the polynomials in the second ring are not the same. This can be checked by defining a map Code: map F=r,0,0,0,x,y,z,w,0,0,;
F(f);F(f)-f; F(g);F(g)-g; |
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