ctrcon-f(3)

ctrcon.f –

Synopsis

Functions/Subroutines

subroutine ctrcon (NORM, UPLO, DIAG, N, A, LDA, RCOND, WORK, RWORK, INFO)
CTRCON

Function/Subroutine Documentation

subroutine ctrcon (characterNORM, characterUPLO, characterDIAG, integerN, complex, dimension( lda, * )A, integerLDA, realRCOND, complex, dimension( * )WORK, real, dimension( * )RWORK, integerINFO)

CTRCON

Purpose:

 CTRCON 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:

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.

UPLO

 UPLO is CHARACTER*1
 = 'U': A is upper triangular;
 = 'L': A is lower triangular.

DIAG

 DIAG is CHARACTER*1
 = 'N': A is non-unit triangular;
 = 'U': A is unit triangular.

 N is INTEGER
 The order of the matrix A. N >= 0.

 A is COMPLEX 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.

LDA

 LDA is INTEGER
 The leading dimension of the array A. LDA >= max(1,N).

RCOND

 RCOND is REAL
 The reciprocal of the condition number of the matrix A,
 computed as RCOND = 1/(norm(A) * norm(inv(A))).

WORK

 WORK is COMPLEX array, dimension (2*N)

RWORK

 RWORK is REAL array, dimension (N)

INFO

 INFO is INTEGER
 = 0: successful exit
 < 0: if INFO = -i, the i-th argument had an illegal value

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 137 of file ctrcon.f.

Author

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