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 righttrack 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
P24 plasma physics
Los Alamos National Laboratory
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Eric Loomis
P24 plasma physics
Los Alamos National Laboratory
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Julie Langou; Research Associate in Computer Science
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Eric Loomis
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