Re: [ublas] [bindings] LAPACK ?GESVD and minimum workspace size

Subject: Re: [ublas] [bindings] LAPACK ?GESVD and minimum workspace size
From: Rutger ter Borg (rutger_at_[hidden])
Date: 2011-04-07 05:17:58

On 04/07/2011 11:01 AM, sguazt wrote:
>
> Hmmm is not so trivial.
 >

I do think it is not trivial, but also not impossible, looking at

http://www.netlib.org/lapack/double/dgesvd.f

and concentrating on the

MINWRK = ****

statements, there's not that much variation. I mean, if there are only N 
variations of MINWRK, we only need N-1 checks, not >20, to see what 
MINWRK should be. I.e., it's max( 3*m+n, 5*n ) in more than 80% of those 
 >20 cases. I'm convinced it probably boils down to a short if-else-tree 
checking the m, n, and job* params.

Cheers,

Rutger