
dtrcon.f(3) LAPACK dtrcon.f(3)
NAME
dtrcon.f 
SYNOPSIS
Functions/Subroutines
subroutine dtrcon (NORM, UPLO, DIAG, N, A, LDA, RCOND, WORK, IWORK, INFO)
DTRCON
Function/Subroutine Documentation
subroutine dtrcon (characterNORM, characterUPLO, characterDIAG, integerN, double precision,
dimension( lda, * )A, integerLDA, double precisionRCOND, double precision, dimension( *
)WORK, integer, dimension( * )IWORK, integerINFO)
DTRCON
Purpose:
DTRCON estimates the reciprocal of the condition number of a
triangular matrix A, in either the 1norm or the infinitynorm.
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 1norm condition number or the
infinitynorm condition number is required:
= '1' or 'O': 1norm;
= 'I': Infinitynorm.
UPLO
UPLO is CHARACTER*1
= 'U': A is upper triangular;
= 'L': A is lower triangular.
DIAG
DIAG is CHARACTER*1
= 'N': A is nonunit triangular;
= 'U': A is unit triangular.
N
N is INTEGER
The order of the matrix A. N >= 0.
A
A is DOUBLE PRECISION array, dimension (LDA,N)
The triangular matrix A. If UPLO = 'U', the leading NbyN
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 NbyN 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 DOUBLE PRECISION
The reciprocal of the condition number of the matrix A,
computed as RCOND = 1/(norm(A) * norm(inv(A))).
WORK
WORK is DOUBLE PRECISION array, dimension (3*N)
IWORK
IWORK is INTEGER array, dimension (N)
INFO
INFO is INTEGER
= 0: successful exit
< 0: if INFO = i, the ith 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 dtrcon.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 dtrcon.f(3) 
