[Numpy-discussion] Zero row in SVD's unitary matrix on some Mac's

Jason Grout jason-sage at creativetrax.com
Thu Apr 28 07:04:52 EDT 2011


On 4/26/11 3:18 PM, Jason Grout wrote:
> On 4/26/11 11:49 AM, Pauli Virtanen wrote:
>> But apparently either there's a bug, or the LAPACK man page needs to
>> be understood as you say.
>
> I've posted a question to the Lapack forum:
>
> http://icl.cs.utk.edu/lapack-forum/viewtopic.php?f=2&t=2402

We've got a reply now:

http://icl.cs.utk.edu/lapack-forum/viewtopic.php?f=2&t=2402

Pauli, you're right that the statement should be parsed as:

"If (JOBZ = 'A') or (JOBZ = 'O' and M >= N), VT contains the N-by-N 
unitary matrix V**H;"

so you're right that the function is written correctly in the case we 
are bringing up (but still has an error in assuming too much when JOBZ 
is not 'A').

We'll work on providing an example with the Accelerate framework and the 
zero row.

Thanks,

Jason




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