# chpcon.f man page

chpcon.f

## Synopsis

### Functions/Subroutines

subroutine chpcon (UPLO, N, AP, IPIV, ANORM, RCOND, WORK, INFO)
CHPCON

## Function/Subroutine Documentation

### subroutine chpcon (character UPLO, integer N, complex, dimension( * ) AP, integer, dimension( * ) IPIV, real ANORM, real RCOND, complex, dimension( * ) WORK, integer INFO)

CHPCON

Purpose:

``` CHPCON estimates the reciprocal of the condition number of a complex
Hermitian packed matrix A using the factorization A = U*D*U**H or
A = L*D*L**H computed by CHPTRF.

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
Specifies whether the details of the factorization are stored
as an upper or lower triangular matrix.
= 'U':  Upper triangular, form is A = U*D*U**H;
= 'L':  Lower triangular, form is A = L*D*L**H.```

N

```          N is INTEGER
The order of the matrix A.  N >= 0.```

AP

```          AP is COMPLEX array, dimension (N*(N+1)/2)
The block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by CHPTRF, stored as a
packed triangular matrix.```

IPIV

```          IPIV is INTEGER array, dimension (N)
Details of the interchanges and the block structure of D
as determined by CHPTRF.```

ANORM

```          ANORM is REAL
The 1-norm of the original matrix A.```

RCOND

```          RCOND 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 1-norm of inv(A) computed in this routine.```

WORK

`          WORK is COMPLEX array, dimension (2*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:

December 2016

Definition at line 120 of file chpcon.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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

Tue Nov 14 2017 Version 3.8.0 LAPACK