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Hi all,

I am using the DSS from MKL to solve the linear system of equations Ax=b, for which the resulting matrix A is sparse and not symmetric, but its structure is symmetric.

Concerning the options, I am using MKL_DSS_SYMMETRIC_STRUCTURE in the definition of the structure and MKL_DSS_INDEFINITE in the factorization.

I am using the following example (15*15 matrix in attachment) to try and solve a system considering that the matrix A is sparse. Unfortunately, the DSS solver gives an error of “MKL-DSS-DSS-Error, Zero Pivot detected”, but the matrix is non-singular. The determinant of the matrix is about -3.1e+62 (calculated in excel) and I get the solution both in excel and matlab.

When I switch the definition of the matrix structure for MKL_DSS_NON_SYMMETRIC, I get the correct solution. I don’t understand why!

In order to understand this problem I create a new subroutine. Using the initial definition of matrix structure, I give all elements of A as non-zero (dense matrix), I am not take advantage of the sparse matrix. With this structure, DSS solver gives the correct solution.

Someone can help me why I cannot use the MKL_DSS_SYMMETRIC_STRUCTURE definition in the sparse matrix structure.

Both subroutines are in attachment.

Thank you.

Diogo

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thanks for the case, it looks like the issue for DSS. we will check the problem on our side and let you know the results soon.

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Hi Diogo,

Yes, we confirmed that this is the bug and the cause of the problem has been found. How important this issue is for you? Can you use the MKL_DSS_NON_SYMMETRIC case as a temporarily workaroud? we expect no performance degradation in that case.

-Gennady

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Hi Gennady,

Thank you for your quick response. I have not problem to use the option MKL_DSS_NON_SYMMETRIC and I check yesterday that the performance is not affected with a simple problem.

Diogo

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well, we will let you know when the original problem would be fixed and which next update. thanks, Gennady

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Diogo,

please check the latest update 1 ( MKL 11.1 Update 1) where the fix of the problem has been provided. Pls let us know if the problem is still there.

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