CUNGQL(3F)CUNGQL(3F)NAME
CUNGQL - generate an M-by-N complex matrix Q with orthonormal columns,
SYNOPSIS
SUBROUTINE CUNGQL( M, N, K, A, LDA, TAU, WORK, LWORK, INFO )
INTEGER INFO, K, LDA, LWORK, M, N
COMPLEX A( LDA, * ), TAU( * ), WORK( LWORK )
PURPOSE
CUNGQL generates an M-by-N complex matrix Q with orthonormal columns,
which is defined as the last N columns of a product of K elementary
reflectors of order M
Q = H(k) . . . H(2)H(1)
as returned by CGEQLF.
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 (n-k+i)-th column must contain the vector which
defines the elementary reflector H(i), for i = 1,2,...,k, as
returned by CGEQLF in the last 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 CGEQLF.
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.
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CUNGQL(3F)CUNGQL(3F)
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an illegal value
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