Hi All,

I have many linear equations derived from flow problem at different time steps. These equations have the same structure (same non-zero entries) but different stiffness matrices and right-hand-sides. The condition number for these matrices are around 4E15, close to ill-conditioned. There seems something wrong with the Pardiso that only the result of the first equation is correct. I have successfully solved these equations by PETSc and exported the results so as to compare.

The parameters used in Pardiso are as follows:

iparm = 0

iparm(1) = 1 ! no solver default

iparm(2) = 2 ! fill-in reordering from METIS

iparm(3) = 0 ! numbers of processors

iparm(4) = 0 ! no iterative-direct algorithm

iparm(5) = 0 ! 0 no user fill-in reducing permutation

iparm(6) = 0 ! =0 solution on the first n compoments of x

iparm(7) = 0 ! not in use

iparm(8) = 9 ! numbers of iterative refinement steps

iparm(9) = 0 ! not in use

iparm(10) = 13 ! perturbe the pivot elements with 1E-13

iparm(11) = 1 ! use nonsymmetric permutation and scaling MPS

iparm(12) = 0 ! not in use

iparm(13) = 1 ! maximum weighted matching algorithm is switched-on (default for non-symmetric)

iparm(14) = 0 ! Output: number of perturbed pivots

iparm(15) = 0 ! not in use

iparm(16) = 0 ! not in use

iparm(17) = 0 ! not in use

iparm(18) = -1 ! Output: number of nonzeros in the factor LU

iparm(19) = -1 ! Output: Mflops for LU factorization

iparm(20) = 0 ! Output: Numbers of CG Iterations

iparm(27) = 0 ! 1: check matrix error

error = 0 ! initialize error flag

msglvl = 0 ! print statistical information

mtype = 11 ! real unsymmetric

For the source codes, data and results, please look into the attached file.

Thanks and Regards,

Daniel