?la_syrpvgrw

Computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.

Syntax

call sla_syrpvgrw( uplo, n, info, a, lda, af, ldaf, ipiv, work )

call dla_syrpvgrw( uplo, n, info, a, lda, af, ldaf, ipiv, work )

call cla_syrpvgrw( uplo, n, info, a, lda, af, ldaf, ipiv, work )

call zla_syrpvgrw( uplo, n, info, a, lda, af, ldaf, ipiv, work )

Include Files

  • mkl.fi

Description

The ?la_syrpvgrw routine computes the reciprocal pivot growth factor norm(A)/norm(U). The max absolute element norm is used. If this is much less than 1, the stability of the LU factorization of the equilibrated matrix A could be poor. This also means that the solution X, estimated condition numbers, and error bounds could be unreliable.

Input Parameters

uplo

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

Specifies the triangle of A to store:

If uplo = 'U', the upper triangle of A is stored,

If uplo = 'L', the lower triangle of A is stored.

n

INTEGER. The number of linear equations, the order of the matrix A; n 0.

info

INTEGER. The value of INFO returned from ?sytrf, that is, the pivot in column info is exactly 0.

a, af

REAL for sla_syrpvgrw

DOUBLE PRECISION for dla_syrpvgrw

COMPLEX for cla_syrpvgrw

DOUBLE COMPLEX for zla_syrpvgrw.

Arrays: a(lda,*), af(ldaf,*).

The array a contains the input n-by-n matrix A. The second dimension of a must be at least max(1,n).

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

The second dimension of af must be at least max(1,n).

lda

INTEGER. The leading dimension of a; lda max(1,n).

ldaf

INTEGER. The leading dimension of af; ldaf max(1,n).

ipiv

INTEGER.

Array, DIMENSION n. Details of the interchanges and the block structure of D as determined by ?sytrf.

work

REAL for sla_syrpvgrw and cla_syrpvgrw

DOUBLE PRECISION for dla_syrpvgrw and zla_syrpvgrw.

Workspace array, dimension 2*n.

See Also

Para obtener información más completa sobre las optimizaciones del compilador, consulte nuestro Aviso de optimización.