Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

ID 766686
Date 12/16/2022
Public

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mkl_pardiso_pivot

Replaces routine which handles Intel® oneAPI Math Kernel Library PARDISO pivots with user-defined routine.

Syntax

call mkl_pardiso_pivot (ai, bi, eps)

Include Files
  • mkl.fi, mkl_pardiso.f90
Description

The mkl_pardiso_pivotroutine allows you to handle diagonal elements which arise during numerical factorization that are zero or near zero. By default, Intel® oneAPI Math Kernel Library PARDISO determines that a diagonal elementbi is a pivot if bi < eps, and if so, replaces it with eps. But you can provide your own routine to modify the resulting factorized matrix in case there are small elements on the diagonal during the factorization step.

NOTE:

To use this routine, you must set iparm(56) to 1 before the main pardiso loop.

NOTE:

This routine is only available for in-core Intel® oneAPI Math Kernel Library PARDISO.

Input Parameters
ai

DOUBLE PRECISION - for real types of matrices (mtype=2, -2, 4, and 6) and for double precision Intel® oneAPI Math Kernel Library PARDISO (iparm(28)=0)

Diagonal element of initial matrix corresponding to pivot element.

bi

DOUBLE PRECISION - for real types of matrices (mtype=2, -2, 4, and 6) and for double precision Intel® oneAPI Math Kernel Library PARDISO (iparm(28)=0)

Diagonal element of factorized matrix that could be chosen as a pivot element.

eps

DOUBLE PRECISION

Scalar to compare with diagonal of factorized matrix. On input equal to parameter described by iparm(10).

Output Parameters
bi

In case element is chosen as a pivot, value with which to replace the pivot.