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man pages->IRIX man pages -> complib/QZHES (3)
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### Contents

```
_QZHES(3F)							    _QZHES(3F)

```

### NAME[Toc][Back]

```     QZHES, SQZHES   -	EISPACK	routine.  This subroutine is the first step of
the QZ algorithm for solving generalized matrix eigenvalue	problems.

```

### SYNOPSYS[Toc][Back]

```	  subroutine  qzhes(nm,	n, a, b, matz, z)
integer	   nm, n
double precision a(nm,n), b(nm,n), z(nm,n)
logical matz

subroutine sqzhes(nm,	n, a, b, matz, z)
integer	   nm, n
real		   a(nm,n), b(nm,n), z(nm,n)
logical matz

```

### DESCRIPTION[Toc][Back]

```     This subroutine accepts a pair of REAL GENERAL matrices and reduces one
of	them to	upper Hessenberg form and the other to upper triangular	form
using orthogonal transformations.	It is usually followed by  QZIT,
QZVAL  and, possibly,  QZVEC.

On	Input

NM	must be	set to the row dimension of two-dimensional array parameters
as	declared in the	calling	program	dimension statement.

N is the order of the matrices.

A contains	a real general matrix.

B contains	a real general matrix.

MATZ should be set	to .TRUE. if the right hand transformations are	to be
accumulated for later use in computing eigenvectors, and to .FALSE.
otherwise.	 On Output

A has been	reduced	to upper Hessenberg form.  The elements	below the
first subdiagonal have been set to	zero.

B has been	reduced	to upper triangular form.  The elements	below the main
diagonal have been	set to zero.

Z contains	the product of the right hand transformations if MATZ has been
set to .TRUE.  Otherwise, Z is not	referenced.  Questions and comments
should be directed	to B. S. Garbow, APPLIED MATHEMATICS DIVISION, ARGONNE
NATIONAL LABORATORY

PPPPaaaaggggeeee 1111```
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