SRC/zpbcon.f(3) | Library Functions Manual | SRC/zpbcon.f(3) |
NAME
SRC/zpbcon.f
SYNOPSIS
Functions/Subroutines
subroutine zpbcon (uplo, n, kd, ab, ldab, anorm, rcond,
work, rwork, info)
ZPBCON
Function/Subroutine Documentation
subroutine zpbcon (character uplo, integer n, integer kd, complex*16, dimension( ldab, * ) ab, integer ldab, double precision anorm, double precision rcond, complex*16, dimension( * ) work, double precision, dimension( * ) rwork, integer info)
ZPBCON
Purpose:
!> !> ZPBCON estimates the reciprocal of the condition number (in the !> 1-norm) of a complex Hermitian positive definite band matrix using !> the Cholesky factorization A = U**H*U or A = L*L**H computed by !> ZPBTRF. !> !> An estimate is obtained for norm(inv(A)), and the reciprocal of the !> condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))). !>
Parameters
UPLO
!> UPLO is CHARACTER*1 !> = 'U': Upper triangular factor stored in AB; !> = 'L': Lower triangular factor stored in AB. !>
N
!> N is INTEGER !> The order of the matrix A. N >= 0. !>
KD
!> KD is INTEGER !> The number of superdiagonals of the matrix A if UPLO = 'U', !> or the number of sub-diagonals if UPLO = 'L'. KD >= 0. !>
AB
!> AB is COMPLEX*16 array, dimension (LDAB,N) !> The triangular factor U or L from the Cholesky factorization !> A = U**H*U or A = L*L**H of the band matrix A, stored in the !> first KD+1 rows of the array. The j-th column of U or L is !> stored in the j-th column of the array AB as follows: !> if UPLO ='U', AB(kd+1+i-j,j) = U(i,j) for max(1,j-kd)<=i<=j; !> if UPLO ='L', AB(1+i-j,j) = L(i,j) for j<=i<=min(n,j+kd). !>
LDAB
!> LDAB is INTEGER !> The leading dimension of the array AB. LDAB >= KD+1. !>
ANORM
!> ANORM is DOUBLE PRECISION !> The 1-norm (or infinity-norm) of the Hermitian band matrix A. !>
RCOND
!> RCOND is DOUBLE PRECISION !> The reciprocal of the condition number of the matrix A, !> computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an !> estimate of the 1-norm of inv(A) computed in this routine. !>
WORK
!> WORK is COMPLEX*16 array, dimension (2*N) !>
RWORK
!> RWORK is DOUBLE PRECISION 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.
Definition at line 131 of file zpbcon.f.
Author
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