Re: Octave hangs forever trying to invert singular matrix

[Carlo de Falco]

On 22 Dec 2009, at 22:23, David Bateman wrote:

> Vic Norton wrote:
> > I don't see how any numerical routine can give you a reasonable  
> > answer.
> > This is a 0/0 problem.
> Giving an unreasonable answer is ok, hanging isn't... This is  
> hanging in
> the CXSparse QR code I presume, but as I was working (admitted very
> slowly) on converting this to use the SPQR code from SuiteSparse, I
> don't think I can be bothered trying to fix this. SPQR is much faster
> and allows a 2-norm solution that is consist with the same case for a
> full matrix,
I just checked and noticed that
full (A)\ones(480,1)
behaves exactly as in matlab so indeed the problem is limited to  
sparse matrices.
As I don't think I have the skills to help you with SPQR I'll  
patiently wait until your work is done.
Thanks!

> D.
c.