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[Lapack] issue with DGGSVD in LAPACK

I was wondering if you could give me an estimate of what size matrix 
I should be able to perform SVD using either dgesvd or dgesdd on a 
machine with a few Gb of RAM?  On both a 2.5 Gb and an 8 Gb machine 
the largest matrix I can use is 500 x 500, any higher and I get a 
segmentation fault.  I use the work space size as suggested in the 
dgesvd and dgesdd routines.


At 8:51 AM -0600 7/9/09, julie langou wrote:
Eric,
I will wait for your output with the new flags.
For info, we just released CLAPACK 3.1.2 a couple of weeks ago, it 
includes all the changes made to LAPACK 3.2.1.
Regards
Julie

On Jul 9, 2009, at 8:40 AM, Eric Loomis wrote:

Thank you very much for your reply.

Regarding your previous email, the reason I chose CLAPACK is 
because I know it best.  I have very limited experience with 
fortran in general and I have not looked into MKL.

I am using the native BLAS that came with the CLAPACK 3.1.1.1 
distribution, which works on my local machine using gcc, but I want 
to get it running on a larger platform and uses icc.  The larger 
platform has ATLAS BLAS which I hope to use in the future.  I would 
also like to get this running in a parallel cluster because I am 
dealing with very large matrices and require a few hundred singular 
values.

As for the error, I run the exact same code on my local machine 
(with gcc) and it works perfectly.

I will try your suggested flags and thanks again for looking into it.

Eric
At 7:22 AM -0600 7/9/09, julie langou wrote:

Eric,

Icc is a picky compiler. Usually we use the following 
flags,-fltconsistency -fp_port

I am not sure this will help much anyway...

Which BLAS library are you using? MKL?

and which LAPACK (c version)? CLAPACK 3.2.1?

I will try to reproduce your problem .


Regarding the error code, if INFO =-4, he is complaining about the 
parameter N.

      SUBROUTINE DGESVD( JOBU, JOBVT, M, N, A, LDA, S, U, LDU, VT, LDVT,
     $                   WORK, LWORK, INFO )

In the code, we are just making sure N is greater than 0.

Maybe you put L in place of N, no?.

      ELSE IF( N.LT.0 ) THEN
         INFO = -4


julie



On Jul 8, 2009, at 11:45 AM, Eric Loomis wrote:


Hello, I ran into a problem building the LAPACK (c version) on a 
high performance computing platform using an icc compiler.  The 
libraries seemed to build okay, but when I ran the testing 
executables I ran into some errors in the SVD routine.  I have 
attached the output file with the errors.  Do you know what may 
have caused these errors?

I have probably a related problem when I try to run some of my 
code using the DGESVD routine in that I get an error
** On entry to DGESVD, parameter number  4 had an illegal value

INFO = -4
LWORK = -1

Can you help me with any of these issues?

thanks.

At 10:21 AM -0700 6/25/09, Zhaojun Bai wrote:

Hi Eric,


I would be happy to try to help out here. Can you let me

the exact formulation of the constrained LS

problem you want to solver? I can take a look and

see whether we're on the right-track to use the DGGSVD

from LAPACK.


Apologize the delay for response. We just finished the spring

quarter term.


Regards,

Zhaojun Bai

UC Davis





Eric Loomis wrote:

Hello,


I am using the routine DGGSVD (CLAPACK) to solve constrained 
least squares problems.  To do this I need to form a matrix X 
from Q and R as discussed in GSVD literature.  R appears to be 
nearly diagonal. The result of using the GSVD to solve a system 
of equations is that the first half of the solution is nearly 
zero, but the second half gives the correct answer.  Can you 
put me in contact with someone familiar with this routine to 
work out this issue?  I can supply the source code if required.




--
Eric Loomis
P-24 plasma physics
Los Alamos National Laboratory
mailstop E526
505-665-3196
<mailto:loomis@Domain.Removed>loomis@Domain.Removed<dsvd.out>_______________________________________________
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**********************************************

Julie Langou; Research Associate in Computer Science

Innovative Computing Laboratory;

University of Tennessee from Denver, Colorado ;-)

<mailto:julie@Domain.Removed>julie@Domain.Removed; 
<http://www.cs.utk.edu/~julie/>http://www.cs.utk.edu/~julie/



--
Eric Loomis
P-24 plasma physics
Los Alamos National Laboratory
mailstop E526
505-665-3196
<mailto:loomis@Domain.Removed>loomis@Domain.Removed


**********************************************
Julie Langou; Research Associate in Computer Science
Innovative Computing Laboratory;
University of Tennessee from Denver, Colorado ;-)
<mailto:julie@Domain.Removed>julie@Domain.Removed; 
<http://www.cs.utk.edu/~julie/>http://www.cs.utk.edu/~julie/


-- 
Eric Loomis
P-24 plasma physics
Los Alamos National Laboratory
mailstop E526
505-665-3196
loomis@Domain.Removed
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