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 zppcon.f(3) LAPACK zppcon.f(3)

zppcon.f -

# SYNOPSIS

## Functions/Subroutines

subroutine zppcon (UPLO, N, AP, ANORM, RCOND, WORK, RWORK, INFO)

ZPPCON

# Function/Subroutine Documentation

## subroutine zppcon (characterUPLO, integerN, complex*16, dimension( * )AP, double precisionANORM, double precisionRCOND, complex*16, dimension( * )WORK, double precision, dimension( * )RWORK, integerINFO)

ZPPCON
Purpose:
``` ZPPCON estimates the reciprocal of the condition number (in the
1-norm) of a complex Hermitian positive definite packed matrix using
the Cholesky factorization A = U**H*U or A = L*L**H computed by
ZPPTRF.

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 triangle of A is stored;
= 'L':  Lower triangle of A is stored.
```
N
```          N is INTEGER
The order of the matrix A.  N >= 0.
```
AP
```          AP is COMPLEX*16 array, dimension (N*(N+1)/2)
The triangular factor U or L from the Cholesky factorization
A = U**H*U or A = L*L**H, packed columnwise in a linear
array.  The j-th column of U or L is stored in the array AP
as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
```
ANORM
```          ANORM is DOUBLE PRECISION
The 1-norm (or infinity-norm) of the Hermitian 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
NAG Ltd.
Date:
November 2011
Definition at line 119 of file zppcon.f.

# Author

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