CPBCON (3)  Linux Manuals
NAME
cpbcon.f 
SYNOPSIS
Functions/Subroutines
subroutine cpbcon (UPLO, N, KD, AB, LDAB, ANORM, RCOND, WORK, RWORK, INFO)
CPBCON
Function/Subroutine Documentation
subroutine cpbcon (characterUPLO, integerN, integerKD, complex, dimension( ldab, * )AB, integerLDAB, realANORM, realRCOND, complex, dimension( * )WORK, real, dimension( * )RWORK, integerINFO)
CPBCON
Purpose:

CPBCON estimates the reciprocal of the condition number (in the 1norm) of a complex Hermitian positive definite band matrix using the Cholesky factorization A = U**H*U or A = L*L**H computed by CPBTRF. 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.
NN is INTEGER The order of the matrix A. N >= 0.
KDKD is INTEGER The number of superdiagonals of the matrix A if UPLO = 'U', or the number of subdiagonals if UPLO = 'L'. KD >= 0.
ABAB is COMPLEX 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 jth column of U or L is stored in the jth column of the array AB as follows: if UPLO ='U', AB(kd+1+ij,j) = U(i,j) for max(1,jkd)<=i<=j; if UPLO ='L', AB(1+ij,j) = L(i,j) for j<=i<=min(n,j+kd).
LDABLDAB is INTEGER The leading dimension of the array AB. LDAB >= KD+1.
ANORMANORM is REAL The 1norm (or infinitynorm) of the Hermitian band matrix A.
RCONDRCOND is REAL The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an estimate of the 1norm of inv(A) computed in this routine.
WORKWORK is COMPLEX array, dimension (2*N)
RWORKRWORK is REAL 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 133 of file cpbcon.f.
Author
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