Additional output of direct sparse solver routines

[erich_riegler]

Hi all,

I want to use the direct sparse solver routines for my (large) least squares adjustment problems. Therefor I would need to get some output of the routines which I did not find in the mkl reference manual (Document Number: 630813-029US).
1) Is there a possibility to get the permutation vector out of the function dss_reorder?
2) Is there a possibility to get the LU factorization of the input matrix?

Many thanks,

Heinz

[Sergey_P_Intel2]

Hi, Heinz!

1) Since MKL 10.2 dss_reorder can return the permutation vector, for this purpose MKL_DSS_GET_ORDER option is used.
2) LU factorization ofthe matrix is stored in internal PARDISO format and cant be accessed. But since MKL 10.1 it is possible to get the result of each (forward and backward) substitution separately. Namely, from the MKL manual:
The parameter opt allows to calculate the final solution step-by-step, calling forward and backward substitutions. If it is set to MKL_DSS_FORWARD_SOLVE - the forward substitution (corresponding to phase =331 in PARDISO) is performed, if it is set to MKL_DSS_DIAGONAL_SOLVE - the diagonal substitution (corresponding to phase =332 in PARDISO) is performed, and if it is set to MKL_DSS_BACKWARD_SOLVE - the backward substitution (corresponding to phase =333 in PARDISO ) is performed. For more details about using these substitutions for different types of matrices, see description of the PARDISO solver.

With best regards,
Sergey