# zpocon.f - Man Page

SRC/zpocon.f

## Synopsis

### Functions/Subroutines

subroutine zpocon (uplo, n, a, lda, anorm, rcond, work, rwork, info)
ZPOCON

## Function/Subroutine Documentation

### subroutine zpocon (character uplo, integer n, complex*16, dimension( lda, * ) a, integer lda, double precision anorm, double precision rcond, complex*16, dimension( * ) work, double precision, dimension( * ) rwork, integer info)

ZPOCON

Purpose:

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

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.```

A

```          A is COMPLEX*16 array, dimension (LDA,N)
The triangular factor U or L from the Cholesky factorization
A = U**H*U or A = L*L**H, as computed by ZPOTRF.```

LDA

```          LDA is INTEGER
The leading dimension of the array A.  LDA >= max(1,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.

Definition at line 119 of file zpocon.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page zpocon(3) is an alias of zpocon.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK