topic Re: Limitation of dsyev was decreased? in Intel® oneAPI Math Kernel Library

Limitation of dsyev was decreased?

akihiro-k — Tue, 26 Feb 2008 09:15:52 GMT

Function dsyev cannot compute eigenvalues of over 81x81 matrix after we update MKL from 9.1.025 to 10.0.1.015.

Function dsyev in MKL 9.1.025 could compute eigenvalues of a matrix (81x81 double) in our environment.

But, the process freezes when the program calls dsyev in MKL 10.0.1.015.

The limitation of matrix size was decreased in MKL 10.x.x ?

Our environment is:

- Intel Core 2 Duo

- 2G Memory

- Windows XP SP2

- VC2005

Re: Limitation of dsyev was decreased?

Todd_R_Intel — Tue, 26 Feb 2008 23:47:54 GMT

I do see a known issue regarding the DSYTRD function (used by DSYEV). If the problem you are seeing is related you should be able to work around this by increasingthe size of your work array to 6*n. Could you give that a try?

-Todd

Re: Limitation of dsyev was decreased?

akihiro-k — Wed, 27 Feb 2008 01:53:02 GMT

Thanks Todd.

We had used (3*n-1) work array, and got errors.

After we malloc 6*n work array, we can compute eigenvalus.

before: dsyev(jobz, uplo, n, a, lda, w, (3n-1 work array), 3n-1, info)

after: dsyev(jobz, uplo, n, a, lda, w, (6n work array), 6n, info)

- Akihiro Kobayashi

Re: Limitation of dsyev was decreased?

Michael_C_Intel4 — Wed, 30 Apr 2008 14:09:24 GMT

Akihiro,

this issue has been fixed in MKL 10.0 Update3, you may turn back to the documented minimal workspace (3*n-1) since Update3, but dsyev would be much faster if you put a recommended workspace size by querying dsyev with lwork=-1.

Michael.