strcon.f (3) - Linux Manuals
NAME
strcon.f -
SYNOPSIS
Functions/Subroutines
subroutine strcon (NORM, UPLO, DIAG, N, A, LDA, RCOND, WORK, IWORK, INFO)
STRCON
Function/Subroutine Documentation
subroutine strcon (characterNORM, characterUPLO, characterDIAG, integerN, real, dimension( lda, * )A, integerLDA, realRCOND, real, dimension( * )WORK, integer, dimension( * )IWORK, integerINFO)
STRCON
Purpose:
-
STRCON estimates the reciprocal of the condition number of a triangular matrix A, in either the 1-norm or the infinity-norm. The norm of A is computed and an estimate is obtained for norm(inv(A)), then the reciprocal of the condition number is computed as RCOND = 1 / ( norm(A) * norm(inv(A)) ).
Parameters:
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NORM
NORM is CHARACTER*1 Specifies whether the 1-norm condition number or the infinity-norm condition number is required: = '1' or 'O': 1-norm; = 'I': Infinity-norm.
UPLOUPLO is CHARACTER*1 = 'U': A is upper triangular; = 'L': A is lower triangular.
DIAGDIAG is CHARACTER*1 = 'N': A is non-unit triangular; = 'U': A is unit triangular.
NN is INTEGER The order of the matrix A. N >= 0.
AA is REAL array, dimension (LDA,N) The triangular matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of the array A contains the upper triangular matrix, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading N-by-N lower triangular part of the array A contains the lower triangular matrix, and the strictly upper triangular part of A is not referenced. If DIAG = 'U', the diagonal elements of A are also not referenced and are assumed to be 1.
LDALDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).
RCONDRCOND is REAL The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).
WORKWORK is REAL array, dimension (3*N)
IWORKIWORK is INTEGER array, dimension (N)
INFOINFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value
Author:
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Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
- November 2011
Definition at line 137 of file strcon.f.
Author
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