CUNG2L - generate an m by n complex matrix Q with
orthonormal columns,
SYNOPSIS
SUBROUTINE CUNG2L( M, N, K, A, LDA, TAU, WORK, INFO )
INTEGER INFO, K, LDA, M, N
COMPLEX A( LDA, * ), TAU( * ), WORK( * )
PURPOSE
CUNG2L generates an m by n complex matrix Q with orthonor
mal 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 ele
mentary reflector H(i), as returned by CGEQLF.
WORK (workspace) COMPLEX array, dimension (N)
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument has an ille
gal value
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