Re: [Lapackpp-devel] LaSVD_IP() Error for only 'sigma' matrix

[Christian S. <sti...@tu...>]

Weird. The parameter number 8 is "LDU: The leading dimension for the array U." 
and the parameter description of "man dgesdd" explains that this parameter is 
active only if "jobz", i.e. the mode of operation, is unequal to "N", but in 
this particular function we've set it to that value. 

The workspace size would be parameter #12. The formula for the workspace size 
is not the same as in my documentation, but it results in a much larger array 
anyway. So this shouldn't be a problem.. or maybe you can play around with it 
a little bit.

Christian

Am Sonntag, 19. Dezember 2004 18:02 schrieb Jacob (Jack) Gryn:
> Hi,
>
> At the time I wrote the e-mail, I didn't have the error output infront of
> me, so I was only trying to get it from memory.  The error was actually as
> follows:
>
> ** On entry to DGESDD parameter number  8 had an illegal value
>
> Jack
>
> -----Original Message-----
> From: Christian Stimming [mailto:sti...@tu...]
> Sent: Sunday, December 19, 2004 8:39 AM
> To: Jacob (Jack) Gryn; lap...@li...
> Subject: Re: [Lapackpp-devel] LaSVD_IP() Error for only 'sigma' matrix
>
> Am Sonntag, 19. Dezember 2004 00:59 schrieb Jacob (Jack) Gryn:
> > The function:
> >
> > void LaSVD_IP(LaGenMatDouble& A, LaVectorDouble &Sigma);
> >
> > When run on a 3x3 matrix, doesn't seem to work, it gives some sort of
>
> error
>
> > about parameter 7 to the lapack call has an invalid parameter.  (Probably
> > lwork again).  For now, I'm just using the call that stores U, Sigma and
> > VT.
>
> The parameter 7 is &U(0,0), i.e. the pointer to the temporary U. I thought
> that one will not be referenced at all. Nevertheless, there might be an
> error
> if U is defined with 0x0 dimension, so that accessing the first element
> gives
> some weird results.
>
> I just changed the code in CVS so that the temporary U and VT have
> dimension
>
> 1x1, so that U(0,0) will return the reference to a valid memory location.
> Hopefully that should fix it.
>
> Christian
>
>
>
>
>
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