DSS debugging

Dishaw__Jim — Thu, 25 Jan 2007 02:21:39 GMT

Let me start by saying I have successfully used the DSS routines and the DSS implementation in the code I am working with does work with a simpler class of problems (1-D geometry).

I have been extending my code to work with 2-D geometry problems, which, from the perspective of the dss routines, results in a larger linear system with some additional non-zero elements. The 1-D geometry results in a penta-diagonal system while the 2-D geometry results in a system with 13 diagonals. The only diagonal that has no zero elements is the main diagonal, which has a value of 1. The other diagonals contain zero and non-zero elements. The matrix is square but it is not symmetric.

The structure of the sparse array from a row perspective has five values. In some cases, it is possible that one of those five values to be zero. When that is the case, the MKL routine dss_factor_real raises a "Zero Pivot detected" error.

I added a routine that uses the row index, columns, and values arrays to write the sparse matrix to a file (in dense form). The matrix has the proper structure, so I am confident that I am populating the three arrays properly. I can also successfully invert the matrix in Mathematica, so I know it is not singular.

If I run the program so that most of the five values per row are non-zero, then dss_factor_real works correctly.

How can I better diagnose why dss_factor_real is generating a "Zero Pivot Detected" error. The only cause I can think of for the "Zero Pivot Detected" error is because the determinant is small, e.g. 2E-6. The only problem with that conclusion is that the determinant is also small when it does work.

Hi,

Tianyu_D_ — Fri, 28 Feb 2014 17:18:44 GMT

Hi,

I met the same problem. I just wonder if you have fixed it.

Regards,

Tianyu

Hi,

Alexander_K_Intel2 — Fri, 28 Feb 2014 17:30:02 GMT

Hi,

What version of MKL do you use and what type of matrix you put to DSS interface?

Thanks,

Alex

it would be much better and

Gennady_F_Intel — Fri, 28 Feb 2014 17:36:55 GMT

it would be much better and faster for investigation and reproducing the problem on our side is to give us the test which we can compile and execute on our side.

topic Hi, in Intel® oneAPI Math Kernel Library

DSS debugging

Hi,

Hi,

it would be much better and