# zupgtr.f - Man Page

SRC/zupgtr.f

## Synopsis

### Functions/Subroutines

subroutine zupgtr (uplo, n, ap, tau, q, ldq, work, info)
ZUPGTR

## Function/Subroutine Documentation

### subroutine zupgtr (character uplo, integer n, complex*16, dimension( * ) ap, complex*16, dimension( * ) tau, complex*16, dimension( ldq, * ) q, integer ldq, complex*16, dimension( * ) work, integer info)

ZUPGTR

Purpose:

``` ZUPGTR generates a complex unitary matrix Q which is defined as the
product of n-1 elementary reflectors H(i) of order n, as returned by
ZHPTRD using packed storage:

if UPLO = 'U', Q = H(n-1) . . . H(2) H(1),

if UPLO = 'L', Q = H(1) H(2) . . . H(n-1).```
Parameters

UPLO

```          UPLO is CHARACTER*1
= 'U': Upper triangular packed storage used in previous
call to ZHPTRD;
= 'L': Lower triangular packed storage used in previous
call to ZHPTRD.```

N

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

AP

```          AP is COMPLEX*16 array, dimension (N*(N+1)/2)
The vectors which define the elementary reflectors, as
returned by ZHPTRD.```

TAU

```          TAU is COMPLEX*16 array, dimension (N-1)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by ZHPTRD.```

Q

```          Q is COMPLEX*16 array, dimension (LDQ,N)
The N-by-N unitary matrix Q.```

LDQ

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

WORK

`          WORK is COMPLEX*16 array, dimension (N-1)`

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 113 of file zupgtr.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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

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