NAME

dorgrq - generate an M-by-N real matrix Q with orthonormal rows,

SYNOPSIS

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

void dorgrq(long int m, long int n, long int k, double ∗da,
long int lda, double ∗tau, long int ∗info)

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

DOUBLE PRECISION A( LDA, ∗ ), TAU( ∗ ), WORK( LWORK )

PURPOSE

DORGRQ generates an M-by-N real 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(2) . . . H(k)
 
as returned by DGERQF.
 

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. N >= M.

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

A       (input/output) DOUBLE PRECISION 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 DGERQF in the last k rows 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) DOUBLE PRECISION array, dimension (K)
TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by DGERQF.

WORK    (workspace/output) DOUBLE PRECISION 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,M). For optimum performance LWORK >= M∗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

Sun, Inc.  —  Last change: 20 Sep 1996