p?laswp

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

p?laswp

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

Syntax

call pslaswp ( direc , rowcol , n , a , ia , ja , desca , k1 , k2 , ipiv )

call pdlaswp ( direc , rowcol , n , a , ia , ja , desca , k1 , k2 , ipiv )

call pclaswp ( direc , rowcol , n , a , ia , ja , desca , k1 , k2 , ipiv )

call pzlaswp ( direc , rowcol , n , a , ia , ja , desca , k1 , k2 , 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) CHARACTER .

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

rowcol

(global) CHARACTER .

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

n

(global) INTEGER .

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 , *) . On entry, this array contains the local pieces of the distributed matrix to which the row/columns interchanges will be applied.

ia

(global) INTEGER .

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

ja

(global) INTEGER .

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

desca

(global and local) INTEGER array of size dlen_ .

The array descriptor for the distributed matrix A .

k1

(global) INTEGER .

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

k2

(global) INTEGER .

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

ipiv

(local)

INTEGER . 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) k and l are to be interchanged .

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 Fortran

p?laswp

Syntax

Include Files

Description

Input Parameters

Output Parameters