[Apologies for cross-posting, I don't know which board would be proper to use]
I am trying to use pardiso to compute the Schur complement of a matrix. I had some stability issues for some large matrices, so I decided to put in a tiny matrix and see if I can figure out the issue. However, it looks like for the small matrix I have, the Schur complement is computed wrong.
This matrix is real symmetric and 8-by-8. The code is attached, and it is commented for ease of reading. Any help is appreciated.
Thank you for the reply. The matrix outputted is wrong, and to my knowledge, it is not even a valid CSR3 matrix.
Here is the correct Schur complement to 3 digits after the point:
// [ 1.667 0.167 -0.204]
// [ 0.167 1.667 0.204]
// [-0.204 0.204 1.500]
You can also find this in the source code, it is provided there for convenience. Since it is symmetric, according to the documentation, Pardiso should return the lower triangular part of this matrix in the CSR3 format.
I am on Fedora Linux, and I am using MKL 2021.3.0.
The issue has been confirmed. We have already escalated it to the engineering team. We will let you know when we receive any information from the engineering team.