cungr2-f(3)

cungr2.f –

Synopsis

Functions/Subroutines

subroutine cungr2 (M, N, K, A, LDA, TAU, WORK, INFO)
CUNGR2 generates all or part of the unitary matrix Q from an RQ factorization determined by cgerqf (unblocked algorithm).

Function/Subroutine Documentation

subroutine cungr2 (integerM, integerN, integerK, complex, dimension( lda, * )A, integerLDA, complex, dimension( * )TAU, complex, dimension( * )WORK, integerINFO)

CUNGR2 generates all or part of the unitary matrix Q from an RQ factorization determined by cgerqf (unblocked algorithm).

Purpose:

 CUNGR2 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 CGERQF.

 

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 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 CGERQF 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 array, dimension (K)
 TAU(i) must contain the scalar factor of the elementary
 reflector H(i), as returned by CGERQF.

WORK

 WORK is COMPLEX 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:

September 2012

Definition at line 115 of file cungr2.f.

Author

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