# zhecon_rook.f man page

zhecon_rook.f —

## Synopsis

### Functions/Subroutines

subroutinezhecon_rook(UPLO, N, A, LDA, IPIV, ANORM, RCOND, WORK, INFO)ZHECON_ROOKestimates the reciprocal of the condition number fort HE matrices using factorization obtained with one of the bounded diagonal pivoting methods (max 2 interchanges)

## Function/Subroutine Documentation

### subroutine zhecon_rook (characterUPLO, integerN, complex*16, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, double precisionANORM, double precisionRCOND, complex*16, dimension( * )WORK, integerINFO)

**ZHECON_ROOK** estimates the reciprocal of the condition number fort HE matrices using factorization obtained with one of the bounded diagonal pivoting methods (max 2 interchanges)

**Purpose:**

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

*A*

```
A is COMPLEX*16 array, dimension (LDA,N)
The block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by CHETRF_ROOK.
```

*LDA*

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

*IPIV*

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

*ANORM*

```
ANORM is DOUBLE PRECISION
The 1-norm 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 1-norm 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 i-th argument had an illegal value
```

**Author:**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**

November 2013

**Contributors:**

November 2013, Igor Kozachenko, Computer Science Division, University of California, Berkeley

September 2007, Sven Hammarling, Nicholas J. Higham, Craig Lucas, School of Mathematics, University of Manchester

Definition at line 139 of file zhecon_rook.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

zhecon_rook(3) is an alias of zhecon_rook.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK