A problem with LU (culaSgetrf)

General CULA Dense (LAPACK & BLAS) support and troubleshooting. Use this forum if you are having a general problem or have encountered a bug.

A problem with LU (culaSgetrf)

Postby LaChupacabra » Tue Feb 02, 2010 11:52 am

Can someone explain to me why culaSgetrf doesn't factorize some matrices, for example a square 5x5 matrix filled with numbers 0..24, I get data error. Matlab, which uses LAPACK can handle such matrices. Is it a bug in CULA? If not, it should be pointed out in the manuals.
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Re:A problem with LU (culaSgetrf)

Postby john » Tue Feb 02, 2010 2:53 pm

We report the error exactly as LAPACK/MKL does - it in defined as an error condition for a matrix to be singular to the getrf routine, and we report it accordingly as a culaDataError. Matlab actually receives this error and disregards it. (Note that the Matlab inv() operator correctly reports it as singular.)

It's worth noting that the L*U*P can still be used to reconstruct A, but you can't solve a system because you will be forced to divide by zero.

I see your point though. LAPACK still provides the factorization, even if singular. CULA 1.2 will include this, as per your finding.

Thanks for the report,
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