CUNGQR(l) LAPACK routine (version 1.1) CUNGQR(l)
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 )
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) 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
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