Opened 14 years ago

Closed 13 years ago

#168 closed bug (fixed)

problems with command 'division'

Reported by: seelisch Owned by: somebody
Priority: minor Milestone: 3-1-1
Component: dontKnow Version: 3-1-0
Keywords: division Cc:


(This trac ticket is based on two emails from markus.lange.hegermann@… received Sept 23, 2009.) unexpected zero entries in U (see attachment); unexpected mismatching matrix dimensions (see attachment)

Change History (2)

comment:1 Changed 14 years ago by seelisch

example with polynomial entries: ========================================= ring RR = 0,(x,y,z),ds;

matrix M[5][6]=[0,x*y-x3*y,0,x4-x6,x3*y-x5*y,x3*z-x5*z, 0,y*z-x2*y*z,0,x3*z-x5*z,x2*y*z-x4*y*z,x2*z2-x4*z2, 0,z-x2*z,x2-x2*y+x*y2-x4-x*y3+x4*y,-x2*y*z,x2*y*z-x*y2*z+x*y3*z-x4*y*z,-x*y*z2, 0,0,-x*y+x*y2-y3+x3*y+y4-x3*y2,x2*z+x*y2*z-x4*z,x*y*z-x*y2*z+y3*z-x3*y*z-y4*z+x3*y2*z,x*z2+y2*z2-x3*z2, 0,0,0,0,0,0 ];

matrix N[5][5]=[0,x*y,0,x4,x3*y,x3*z, 0,y*z,0,x3*z,x2*y*z,x2*z2, -x*y,z,x2-x2*y+x*y2,-x2*y*z,x2*y*z-x*y2*z,-x*y*z2, y2,0,-x*y+x*y2-y3,x2*z+x*y2*z,x*y*z-x*y2*z+y3*z,x*z2+y2*z2, 1-x2,0,-y2+x2*y,-x3*z,y2*z-x2*y*z,-x2*z2 ];

list l=division(M,N);

matrix T=l[1]; matrix R=l[2]; matrix U=l[3];

U should be a diagonal matrix of units print(U);

but the first column of M is zero print(M);

=========================================== example with number entries: =========================================== ring RR = 0,(x),ds;

matrix M[2][2]=[1,0,0,0];

matrix NN[2][1]=[1,0]; module N=std(NN);

list l=division(M,N);

matrix T=l[1]; matrix R=l[2]; matrix U=l[3];

print("matrix(M)*U"); print(matrix(M)*U); print("matrix(N)*T+matrix(R)"); print(matrix(N)*T+matrix(R));

print("M"); print(M); print("N"); print(N); print("T"); print(T); R should have the same dimension as M print("R"); print(R); here again a zero is given instead of a unit print("U"); print(U);

matrix R2=reduce(M,N); R2 should have the same dimension as M print("R2"); print(R2);

comment:2 Changed 13 years ago by hannes

Resolution: fixed
Status: newclosed

2 problems: - size of result matrices in reduce and division: fixed

  • shall U be filled with 1 in unused places ? yes (according to the manual)
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