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zungr2.f(3) LAPACK zungr2.f(3)

NAME

zungr2.f

SYNOPSIS

Functions/Subroutines


subroutine zungr2 (M, N, K, A, LDA, TAU, WORK, INFO)
ZUNGR2 generates all or part of the unitary matrix Q from an RQ factorization determined by cgerqf (unblocked algorithm).

Function/Subroutine Documentation

subroutine zungr2 (integer M, integer N, integer K, complex*16, dimension( lda, * ) A, integer LDA, complex*16, dimension( * ) TAU, complex*16, dimension( * ) WORK, integer INFO)

ZUNGR2 generates all or part of the unitary matrix Q from an RQ factorization determined by cgerqf (unblocked algorithm).

Purpose:


ZUNGR2 generates an m by n complex matrix Q with orthonormal rows,
which is defined as the last m rows of a product of k elementary
reflectors of order n
Q = H(1)**H H(2)**H . . . H(k)**H
as returned by ZGERQF.

Parameters:

M


M is INTEGER
The number of rows of the matrix Q. M >= 0.

N


N is INTEGER
The number of columns of the matrix Q. N >= M.

K


K is INTEGER
The number of elementary reflectors whose product defines the
matrix Q. M >= K >= 0.

A


A is COMPLEX*16 array, dimension (LDA,N)
On entry, the (m-k+i)-th row must contain the vector which
defines the elementary reflector H(i), for i = 1,2,...,k, as
returned by ZGERQF in the last k rows of its array argument
A.
On exit, the m-by-n matrix Q.

LDA


LDA is INTEGER
The first dimension of the array A. LDA >= max(1,M).

TAU


TAU is COMPLEX*16 array, dimension (K)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by ZGERQF.

WORK


WORK is COMPLEX*16 array, dimension (M)

INFO


INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an illegal value

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

December 2016

Definition at line 116 of file zungr2.f.

Author

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Tue Nov 14 2017 Version 3.8.0