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Beginner
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MKL 10.3 Beta: clapack_dgbtrf

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 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 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....
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Employee
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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

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Beginner
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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
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Moderator
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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

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Moderator
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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

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