Re: svd

[Jaroslav Hajek]

On Mon, Jun 14, 2010 at 9:06 AM, Carlo de Falco <address@hidden> wrote:
>
> On 14 Jun 2010, at 04:22, Tatsuro MATSUOKA wrote:
>
>> Hello
>>
>> I have carried out on the mingw platform. The situation seems to be
>> the same.
>>
>>
>> Octave-3.2.4(Bejamin altas 3.8.2)
>> octave:1> a=randn(1000);
>> octave:2> tic; svd(a); toc
>> Elapsed time is 3.76562 seconds.
>> octave:3> tic; [u,s,v] = svd(a); toc
>> Elapsed time is 25.2969 seconds.
>>
>> 3.3.51+(Build myself on May 26, 2010, altas 3.8.2)
>> octave.exe:1> a=randn(1000);
>> octave.exe:2> tic; svd(a); toc
>> Elapsed time is 3.01562 seconds.
>> octave.exe:3> tic; [u,s,v] = svd(a); toc
>> Elapsed time is 25.2344 seconds.
>>
>> Regards
>>
>> Tatsuro
>
> FWIW:
>
>  >> a = randn (1000);
>  >> tic; svd(a); toc
> Elapsed time is 2.126371 seconds.
>  >> tic; [u,s,v]=svd(a); toc
> Elapsed time is 16.446979 seconds.
>  >> version
>
> ans =
>
> 7.5.0.338 (R2007b)
>
>  >>
>
> c.
>

Try (with development version):

octave:1> a = randn (1000);
octave:2> tic; svd(a); toc
Elapsed time is 0.743829 seconds.
octave:3> tic; [u,s,v]=svd(a); toc
Elapsed time is 10.1483 seconds.
octave:4> svd_driver ("gesdd")
octave:5> tic; svd(a); toc
Elapsed time is 0.734863 seconds.
octave:6> tic; [u,s,v]=svd(a); toc
Elapsed time is 1.66164 seconds.

See bug #29487.

hth

-- 
RNDr. Jaroslav Hajek, PhD
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz