strcon (l) - Linux Man Page

strcon: estimates the reciprocal of the condition number of a triangular matrix A, in either the 1-norm or the infinity-norm


On Linux: $ man l strcon
Index of strcon man page
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NAME

STRCON - estimates the reciprocal of the condition number of a triangular matrix A, in either the 1-norm or the infinity-norm  

SYNOPSIS

SUBROUTINE STRCON(
NORM, UPLO, DIAG, N, A, LDA, RCOND, WORK, IWORK, INFO )

    
CHARACTER DIAG, NORM, UPLO

    
INTEGER INFO, LDA, N

    
REAL RCOND

    
INTEGER IWORK( * )

    
REAL A( LDA, * ), WORK( * )
 

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)) ).
 

ARGUMENTS

NORM (input) CHARACTER*1
Specifies whether the 1-norm condition number or the infinity-norm condition number is required:
= aq1aq or aqOaq: 1-norm;
= aqIaq: Infinity-norm.
UPLO (input) CHARACTER*1

= aqUaq: A is upper triangular;
= aqLaq: A is lower triangular.
DIAG (input) CHARACTER*1

= aqNaq: A is non-unit triangular;
= aqUaq: A is unit triangular.
N (input) INTEGER
The order of the matrix A. N >= 0.
A (input) REAL array, dimension (LDA,N)
The triangular matrix A. If UPLO = aqUaq, 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 = aqLaq, 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 = aqUaq, the diagonal elements of A are also not referenced and are assumed to be 1.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
RCOND (output) REAL
The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).
WORK (workspace) REAL array, dimension (3*N)
IWORK (workspace) INTEGER array, dimension (N)
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value


 

Index

NAME
SYNOPSIS
PURPOSE
ARGUMENTS

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