?syswapr1

Syntax

FORTRAN 77:

call ssyswapr1( uplo, n, a, i1, i2 )

call dsyswapr1( uplo, n, a, i1, i2 )

call csyswapr1( uplo, n, a, i1, i2 )

call zsyswapr1( uplo, n, a, i1, i2 )

Fortran 95:

call syswapr1( a,i1,i2[,uplo] )

Include Files

The FORTRAN 77 interfaces are specified in the mkl_lapack.fi and mkl_lapack.h include files, and the Fortran 95 interfaces are specified in the lapack.f90 include file.

Description

The routine applies an elementary permutation on the rows and columns of a symmetric matrix.

Input Parameters

uplo

CHARACTER*1. Must be 'U' or 'L'.

Indicates how the input matrix A has been factored:

If uplo = 'U', the array a stores the upper triangular factor U of the factorization A = U*D*U^T.

If uplo = 'L', the array a stores the lower triangular factor L of the factorization A = L*D*L^T.

n

INTEGER. The order of matrix A; n ≥ 0.

nrhs

INTEGER. The number of right-hand sides; nrhs ≥ 0.

a

REAL for ssyswapr1

DOUBLE PRECISION for dsyswapr1

COMPLEX for csyswapr1

DOUBLE COMPLEX for zsyswapr1

Array of dimension (lda,n).

The array a contains the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by ?sytrf.

lda

INTEGER. The leading dimension of the array a. lda ≥ max(1,n).

i1

INTEGER. Index of the first row to swap.

i2

INTEGER. Index of the second row to swap.

Output Parameters

a

If info = 0, the symmetric inverse of the original matrix.

If info = 'U', the upper triangular part of the inverse is formed and the part of A below the diagonal is not referenced.

If info = 'L', the lower triangular part of the inverse is formed and the part of A above the diagonal is not referenced.

Fortran 95 Interface Notes

Routines in Fortran 95 interface have fewer arguments in the calling sequence than their FORTRAN 77 counterparts. For general conventions applied to skip redundant or reconstructible arguments, see Fortran 95 Interface Conventions.

Specific details for the routine syswapr1 interface are as follows:

a

Holds the matrix A of size (n, n).

i1

Holds the index for swap.

i2

Holds the index for swap.

uplo

Indicates how the matrix A has been factored. Must be 'U' or 'L'.