p?laswp

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 10/15/2026

Version

Public

p?laswp

Performs a series of row interchanges on a general rectangular matrix.

Syntax

void pslaswp(char *direc, char *rowcol, MKL_INT *n, float *a, MKL_INT *ia, MKL_INT *ja,
             MKL_INT *desca, MKL_INT *k1, MKL_INT *k2, MKL_INT *ipiv);

void pdlaswp(char *direc, char *rowcol, MKL_INT *n, double *a, MKL_INT *ia, MKL_INT *ja,
             MKL_INT *desca, MKL_INT *k1, MKL_INT *k2, MKL_INT *ipiv);

void pclaswp(char *direc, char *rowcol, MKL_INT *n, MKL_Complex8 *a, MKL_INT *ia,
             MKL_INT *ja, MKL_INT *desca, MKL_INT *k1, MKL_INT *k2, MKL_INT *ipiv);

void pzlaswp(char *direc, char *rowcol, MKL_INT *n, MKL_Complex16 *a, MKL_INT *ia,
             MKL_INT *ja, MKL_INT *desca, MKL_INT *k1, MKL_INT *k2, MKL_INT *ipiv);

Include Files

mkl_scalapack.h

Description

pslaswp pdlaswp pclaswp pzlaswp The p?laswp routine function performs a series of row or column interchanges on the distributed matrix sub(A)=A(ia:ia+n-1, ja:ja+n-1) . One interchange is initiated for each of rows or columns k1 through k2 of sub( A ). This routine function assumes that the pivoting information has already been broadcast along the process row or column. Also note that this routine function will only work for k1-k2 being in the same mb (or nb ) block. If you want to pivot a full matrix, use p?lapiv (Applies a permutation matrix to a general distributed matrix, resulting in row or column pivoting.) .

Input Parameters

direc

(global)

Specifies in which order the permutation is applied: = ‘F’ - forward, = ‘B’ - backward.

rowcol

(global)

Specifies if the rows or columns are permuted: = ‘R’ - rows, = ‘C’ - columns.

n

(global)

If rowcol='R' , the length of the rows of the distributed matrix A(*, ja:ja+n-1) to be permuted; If rowcol='C' , the length of the columns of the distributed matrix A(ia:ia+n-1 , *) to be permuted;

a

(local) REAL for pslaswp DOUBLE PRECISION for pdlaswp COMPLEX for pclaswp COMPLEX*16 for pzlaswp .

Pointer into the local memory to an array of size lld_a * LOCc ( n_a ) . On entry, this array contains the local pieces of the distributed matrix to which the row/columns interchanges will be applied.

ia

(global)

The row index in the global matrix A indicating the first row of sub( A ).

ja

(global)

The column index in the global matrix A indicating the first column of sub( A ).

desca

(global and local) array of size dlen_ .

The array descriptor for the distributed matrix A .

k1

(global)

The first element of ipiv for which a row or column interchange will be done.

k2

(global)

The last element of ipiv for which a row or column interchange will be done.

ipiv

(local)

Array of size LOCr(m_a)+mb_a for row pivoting and LOCr(n_a)+nb_a for column pivoting. This array is tied to the matrix A , ipiv(k)[k]=l implies rows (or columns) kk +1 and l are to be interchanged , k = 0, 1, …, size ( ipiv ) -1 .

Output Parameters

A: (local) REAL for pslaswp DOUBLE PRECISION for pdlaswp COMPLEX for pclaswp COMPLEX*16 for pzlaswp . On exit, the permuted distributed matrix.

NOTE:

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Developer Reference for Intel® oneAPI Math Kernel Library for C

p?laswp

Syntax

Include Files

Description

Input Parameters

Output Parameters