STPCON (3)  Linux Manuals
NAME
stpcon.f 
SYNOPSIS
Functions/Subroutines
subroutine stpcon (NORM, UPLO, DIAG, N, AP, RCOND, WORK, IWORK, INFO)
STPCON
Function/Subroutine Documentation
subroutine stpcon (characterNORM, characterUPLO, characterDIAG, integerN, real, dimension( * )AP, realRCOND, real, dimension( * )WORK, integer, dimension( * )IWORK, integerINFO)
STPCON
Purpose:

STPCON estimates the reciprocal of the condition number of a packed 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.
UPLOUPLO is CHARACTER*1 = 'U': A is upper triangular; = 'L': A is lower triangular.
DIAGDIAG is CHARACTER*1 = 'N': A is nonunit triangular; = 'U': A is unit triangular.
NN is INTEGER The order of the matrix A. N >= 0.
APAP is REAL array, dimension (N*(N+1)/2) The upper or lower triangular matrix A, packed columnwise in a linear array. The jth column of A is stored in the array AP as follows: if UPLO = 'U', AP(i + (j1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j1)*(2nj)/2) = A(i,j) for j<=i<=n. If DIAG = 'U', the diagonal elements of A are not referenced and are assumed to be 1.
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 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 130 of file stpcon.f.
Author
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