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

5 posts
• Page **1** of **1**

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

I want to find the nontrivial solutions of the complex general matrix. Can I use zgsevd routine? Is it always helpful?

Bests,

Zahra

- Zahra
**Posts:**13**Joined:**Fri May 09, 2008 1:11 pm

Yes you may use ZGESVD to compute an orthogonal basis for the Nullspace of a complex general matrix.

Julien.

Julien.

Last edited by Julien Langou on Fri Feb 03, 2012 4:48 pm, edited 1 time in total.

- Julien Langou
**Posts:**821**Joined:**Thu Dec 09, 2004 12:32 pm**Location:**Denver, CO, USA

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.

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.

- Zahra
**Posts:**13**Joined:**Fri May 09, 2008 1:11 pm

X is the 16th column of the VT matrix in your case.

(Please check that S(16) is indeed small, and that AX = 0.)

(Please check that S(16) is indeed small, and that AX = 0.)

- Julien Langou
**Posts:**821**Joined:**Thu Dec 09, 2004 12:32 pm**Location:**Denver, CO, USA

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

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

- Zahra
**Posts:**13**Joined:**Fri May 09, 2008 1:11 pm

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