Places pointers dedicated for sparse representation of a requested matrix (values, rows, and columns) into MKL PARDISO
void pardiso_export (const _MKL_DSS_HANDLE_t pt, void* values, MKL_INT* rows, MKL_INT* columns, MKL_INT* step, MKL_INT* iparm, MKL_INT* error);
This auxiliary routine places pointers dedicated for sparse representation of a requested matrix (values, rows, and columns) into MKL PARDISO. The matrix will be stored in the three-array variant of the compressed sparse row (CSR3 format) with 0-based indexing.
Currently, this routine can be used only for a sparse Schur complement matrix. All parameters related to the Schur complement matrix (perm, iparm) must be set before the reordering stage of MKL PARDISO (phase = 11) is called.
pt |
Array with a size of 64. Handle to internal data structure for the Intel® MKL PARDISO solver. The entries must be set to zero prior to the first call to pardiso. Unique for factorization. |
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iparm |
This array is used to pass various parameters to Intel® MKL PARDISO and to return some useful information after execution of the solver. |
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step |
Stage indicator. These are the currently supported values:
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values |
Parameter type: input/output parameter. This array contains the non-zero elements of the requested matrix. |
rows |
Parameter type: input/output parameter. Array of size (size + 1) For CSR3 format, rows[i] ( i < size ) points to the first column index of row i in the array columns; that is, rows[i] gives the index of the element in the array values that contains the first non-zero element from row i of the sparse matrix. The last element, rows[size], is equal to the number of non-zero elements in the sparse matrix. |
columns |
Parameter type: input/output parameter. This array contains the column indices for the non-zero elements of the requested matrix. |
error |
Parameter type: output parameter. The error status:
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The following C-style example demonstrates how to use the pardiso_export routine to get the sparse representation (that is, three-array CSR format) of a Schur complement matrix.
#include "mkl.h"
/*
* Call the reordering phase of MKL PARDISO with iparm[35] set to -1 in
* order to compute the Schur complement matrix only, or -2 to compute all
* factorization arrays. perm array indices related to the Schur complement
* matrix must be set to 1.
*/
phase = 11;
for ( i = 0; i < schur_size; i++ ) { perm[i] = 1.; }
iparm[35] = -1;
pardiso(pt, &maxfct, &mnum, &mtype, &phase, &n, a, ia, ja, perm, &nrhs,
iparm, &msglvl, b, x, &error);
/*
* After the reordering phase, iparm[35] will contain the number of non-zero
* elements for the Schur complement matrix. Arrays dedicated to the sparse
* representation of the Schur complement matrix must be allocated before
* the factorization stage of MKL PARDISO is called.
*/
schur_nnz = iparm[35];
schur_rows = (MKL_INT *) mkl_malloc(schur_size+1, ALIGNMENT);
schur_columns = (MKL_INT *) mkl_malloc(schur_nnz , ALIGNMENT);
schur_values = (DATA_TYPE *) mkl_malloc(schur_nnz , ALIGNMENT);
/*
* Call to the pardiso_export routine with step equal to 1 in order to put
* pointers related to the three-array CSR format into MKL PARDISO:
*/
pardiso_export(pt, schur_values, schur_ia, schur_ja, &step, iparm, &error);
/*
* Call the factorization phase of PARDISO with iparm[35] equal to -1 or -2
* to compute the Schur complement matrix:
*/
phase = 22;
iparm[35] = -1;
pardiso(pt, &maxfct, &mnum, &mtype, &phase, &n, a, ia, ja, perm, &nrhs,
iparm, &msglvl, b, x, &error);
/*
* After the factorization stage, schur_values, schur_rows, and
* schur_columns will contain the Schur complement matrix in CSR3 format.
*/