NAME

cungqr - generate an M-by-N complex matrix Q with orthonormal columns,

SYNOPSIS

SUBROUTINE CUNGQR( M, N, K, A, LDA, TAU, WORK, LWORK, INFO )

INTEGER INFO, K, LDA, LWORK, M, N

COMPLEX A( LDA, ∗ ), TAU( ∗ ), WORK( LWORK )

#include <sunperf.h>

void cungqr(int m, int n, int k, complex ∗ca, int lda, complex ∗tau, int ∗info) ;

PURPOSE

CUNGQR 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.
 

ARGUMENTS

M (input) INTEGER
The number of rows of the matrix Q. M >= 0.

N (input) INTEGER
The number of columns of the matrix Q. M >= N >= 0.

K (input) INTEGER
The number of elementary reflectors whose product defines the matrix Q. N >= K >= 0.

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

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

WORK (workspace/output) COMPLEX array, dimension (LWORK)
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

LWORK (input) INTEGER
The dimension of the array WORK. LWORK >= max(1,N). For optimum performance LWORK >= N∗NB, where NB is the optimal blocksize.

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

SunOS 5.0  —  Last change: 10 Dec 1998