dtbcon (3)  Linux Manuals
NAME
dtbcon.f 
SYNOPSIS
Functions/Subroutines
subroutine dtbcon (NORM, UPLO, DIAG, N, KD, AB, LDAB, RCOND, WORK, IWORK, INFO)
DTBCON
Function/Subroutine Documentation
subroutine dtbcon (characterNORM, characterUPLO, characterDIAG, integerN, integerKD, double precision, dimension( ldab, * )AB, integerLDAB, double precisionRCOND, double precision, dimension( * )WORK, integer, dimension( * )IWORK, integerINFO)
DTBCON
Purpose:

DTBCON estimates the reciprocal of the condition number of a triangular band 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.
KDKD is INTEGER The number of superdiagonals or subdiagonals of the triangular band matrix A. KD >= 0.
ABAB is DOUBLE PRECISION array, dimension (LDAB,N) The upper or lower triangular band matrix A, stored in the first kd+1 rows of the array. The jth column of A is stored in the jth column of the array AB as follows: if UPLO = 'U', AB(kd+1+ij,j) = A(i,j) for max(1,jkd)<=i<=j; if UPLO = 'L', AB(1+ij,j) = A(i,j) for j<=i<=min(n,j+kd). If DIAG = 'U', the diagonal elements of A are not referenced and are assumed to be 1.
LDABLDAB is INTEGER The leading dimension of the array AB. LDAB >= KD+1.
RCONDRCOND is DOUBLE PRECISION The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).
WORKWORK is DOUBLE PRECISION 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 143 of file dtbcon.f.
Author
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