topic MKL 10.3 Beta: clapack_dgbtrf in Intel® oneAPI Math Kernel Library

MKL 10.3 Beta: clapack_dgbtrf

brodman — Wed, 30 Jun 2010 20:29:11 GMT

Hi, I'm trying out the 10.3 beta's c support for lapack. I'm having issues with using clapack_dgbtrf with CLAPACK_ROW_MAJOR data layout. My simple example is a 4x4 matrix with 2 upper and lower diagonals, stored in banded form. The main diagonal has hte value 1.1 and the off diagonals have the value -.01.

If I create this matrix using column major layout and call the function as follows:

clapack_dgbtrf(CLAPACK_COL_MAJOR, 4, 4, 2, 2, colA, 7, ipiv);

The following correct result is observed:

x x x x

x x -.01 -.01

x -.01 -.0100909 -.0100917

1.1 1.09991 1.09982 1.09982

-.00909091 -.00917431 -.0091754 x

-.00909091 -.00909166 x x

However, if I store the matrix using row major data layout and call the function:

clapack_dgbtrf(CLAPACK_ROW_MAJOR, 4, 4, 2, 2, rowA, 4, ipiv);

I get:

x x x x

x x -.01 -.01

x -.01 -.0100909 -.0100917

1.1 1.09991 1.09982 1.1

-.00909091 -.00917431 -.01 x

-.00909091 -.01 x x

I'm not sure if I'm doing something incorrectly, or whether the code itself might have a < instead of a <= or something....

Edit: When calling the routine with row major layout, the return value is 4.

Any help would be appreciated....

clapack_dgbtrf

Ying_H_Intel — Thu, 01 Jul 2010 04:14:49 GMT

Hello ~

Could you please attach a small c code for the problem?
If try clapack_dgbtrf(CLAPACK_ROW_MAJOR, 4, 4, 2, 2, rowA, 7, ipiv); what is the return value ?

Regards,
Ying

clapack_dgbtrf

brodman — Thu, 01 Jul 2010 14:48:53 GMT

If I change the LDA parameter to 7, it's just completely wrong and returns 1.

The source is attached. I build it with:

icc -O2 -o ultest ultest.cpp -lmkl_sequential -lmkl_core -lmkl_intel_lp64

clapack_dgbtrf

Gennady_F_Intel — Tue, 06 Jul 2010 09:19:43 GMT

brodman,

your original version was correct. I mean this call:

clapack_dgbtrf(CLAPACK_ROW_MAJOR, 4, 4, 2, 2, rowA, 4, ipiv);

another words, LDA have to be == 4.

Thanks for the test. I will check the problem on our side and will back asap.

--Gennady

MKL 10.3 Beta: clapack_dgbtrf

Gennady_F_Intel — Tue, 06 Jul 2010 09:40:03 GMT

Hi Brodman,
This is the error. This issue has been submitted to our internal development tracking database for further investigation, we will inform you once a new update becomes available.Here is a bug tracking number for your reference:

DPD200186873

Regards, Gennady