
zgtcon.f(3) LAPACK zgtcon.f(3)
NAME
zgtcon.f 
SYNOPSIS
Functions/Subroutines
subroutine zgtcon (NORM, N, DL, D, DU, DU2, IPIV, ANORM, RCOND, WORK, INFO)
ZGTCON
Function/Subroutine Documentation
subroutine zgtcon (characterNORM, integerN, complex*16, dimension( * )DL, complex*16,
dimension( * )D, complex*16, dimension( * )DU, complex*16, dimension( * )DU2, integer,
dimension( * )IPIV, double precisionANORM, double precisionRCOND, complex*16, dimension( *
)WORK, integerINFO)
ZGTCON
Purpose:
ZGTCON estimates the reciprocal of the condition number of a complex
tridiagonal matrix A using the LU factorization as computed by
ZGTTRF.
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:
NORM
NORM is CHARACTER*1
Specifies whether the 1norm condition number or the
infinitynorm condition number is required:
= '1' or 'O': 1norm;
= 'I': Infinitynorm.
N
N is INTEGER
The order of the matrix A. N >= 0.
DL
DL is COMPLEX*16 array, dimension (N1)
The (n1) multipliers that define the matrix L from the
LU factorization of A as computed by ZGTTRF.
D
D is COMPLEX*16 array, dimension (N)
The n diagonal elements of the upper triangular matrix U from
the LU factorization of A.
DU
DU is COMPLEX*16 array, dimension (N1)
The (n1) elements of the first superdiagonal of U.
DU2
DU2 is COMPLEX*16 array, dimension (N2)
The (n2) elements of the second superdiagonal of U.
IPIV
IPIV is INTEGER array, dimension (N)
The pivot indices; for 1 <= i <= n, row i of the matrix was
interchanged with row IPIV(i). IPIV(i) will always be either
i or i+1; IPIV(i) = i indicates a row interchange was not
required.
ANORM
ANORM is DOUBLE PRECISION
If NORM = '1' or 'O', the 1norm of the original matrix A.
If NORM = 'I', the infinitynorm of the original 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 1norm of inv(A) computed in this routine.
WORK
WORK is COMPLEX*16 array, dimension (2*N)
INFO
INFO 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:
September 2012
Definition at line 141 of file zgtcon.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 zgtcon.f(3) 
