# cung2r.f

## NAME

cung2r.f −

## SYNOPSIS

**Functions/Subroutines**

subroutine **cung2r** (M, N, K, A, LDA, TAU, WORK, INFO)

CUNG2R

## Function/Subroutine Documentation

**subroutine cung2r (integerM, integerN, integerK, complex, dimension( lda, * )A, integerLDA, complex, dimension( * )TAU, complex, dimension( * )WORK, integerINFO)**

CUNG2R

**Purpose:**

CUNG2R generates an m by n complex matrix Q with orthonormal columns,

which is defined as the first n columns of a product of k elementary

reflectors of order m

Q = H(1) H(2) . . . H(k)

as returned by CGEQRF.

**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. M >= N >= 0.

*K*

K is INTEGER

The number of elementary reflectors whose product defines the

matrix Q. N >= K >= 0.

*A*

A is COMPLEX array, dimension (LDA,N)

On entry, the i-th column must contain the vector which

defines the elementary reflector H(i), for i = 1,2,...,k, as

returned by CGEQRF in the first k columns 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 array, dimension (K)

TAU(i) must contain the scalar factor of the elementary

reflector H(i), as returned by CGEQRF.

*WORK*

WORK is COMPLEX array, dimension (N)

*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:**

November 2011

Definition at line 115 of file cung2r.f.

## Author

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