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zgsevd for Ax=0
Posted:
Tue Jan 31, 2012 1:45 amby Zahra
Dear all,
I want to find the nontrivial solutions of the complex general matrix. Can I use zgsevd routine? Is it always helpful?
Bests,
Zahra
Re: zgsevd for Ax=0
Posted:
Tue Jan 31, 2012 11:16 amby Julien Langou
Yes you may use ZGESVD to compute an orthogonal basis for the Nullspace of a complex general matrix.
Julien.
Re: zgsevd for Ax=0
Posted:
Fri Feb 03, 2012 4:45 pmby Zahra
thank you very much for your reply. I found somewhere that
The columns of V corresponding to zero elements of D span the null-space
I have 16by16 matrix. Would you please let me know that the parameter which shows the x is a column of U or V?
Bests.
Re: zgsevd for Ax=0
Posted:
Fri Feb 03, 2012 4:56 pmby Julien Langou
X is the 16th column of the VT matrix in your case.
(Please check that S(16) is indeed small, and that AX = 0.)
Re: zgsevd for Ax=0
Posted:
Wed Feb 08, 2012 2:55 amby Zahra
Dear Julien,
I used the routine for finding the X of AX=0. But while S(16) is small (in order of 10^-8), AX is of order of 10^-1. Here, I've taken the 16 column of VT to be X. Indeed this X can't be the solution of AX=0. Am I doing something wrong? would you please help?
Also, is there any other method that I can use to find the nontrivial solutions of AX=0?
Bests