ZUNMLQ(l) ) ZUNMLQ(l)NAME
ZUNMLQ - overwrite the general complex M-by-N matrix C with SIDE = 'L'
SIDE = 'R' TRANS = 'N'
SYNOPSIS
SUBROUTINE ZUNMLQ( SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK,
LWORK, INFO )
CHARACTER SIDE, TRANS
INTEGER INFO, K, LDA, LDC, LWORK, M, N
COMPLEX*16 A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
PURPOSE
ZUNMLQ overwrites the general complex M-by-N matrix C with SIDE = 'L'
SIDE = 'R' TRANS = 'N': Q * C C * Q TRANS = 'C': Q**H * C C
* Q**H
where Q is a complex unitary matrix defined as the product of k elemen‐
tary reflectors
Q = H(k)' . . . H(2)' H(1)'
as returned by ZGELQF. Q is of order M if SIDE = 'L' and of order N if
SIDE = 'R'.
ARGUMENTS
SIDE (input) CHARACTER*1
= 'L': apply Q or Q**H from the Left;
= 'R': apply Q or Q**H from the Right.
TRANS (input) CHARACTER*1
= 'N': No transpose, apply Q;
= 'C': Conjugate transpose, apply Q**H.
M (input) INTEGER
The number of rows of the matrix C. M >= 0.
N (input) INTEGER
The number of columns of the matrix C. N >= 0.
K (input) INTEGER
The number of elementary reflectors whose product defines the
matrix Q. If SIDE = 'L', M >= K >= 0; if SIDE = 'R', N >= K >=
0.
A (input) COMPLEX*16 array, dimension
(LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R' The i-th row must
contain the vector which defines the elementary reflector H(i),
for i = 1,2,...,k, as returned by ZGELQF in the first k rows of
its array argument A. A is modified by the routine but
restored on exit.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,K).
TAU (input) COMPLEX*16 array, dimension (K)
TAU(i) must contain the scalar factor of the elementary reflec‐
tor H(i), as returned by ZGELQF.
C (input/output) COMPLEX*16 array, dimension (LDC,N)
On entry, the M-by-N matrix C. On exit, C is overwritten by
Q*C or Q**H*C or C*Q**H or C*Q.
LDC (input) INTEGER
The leading dimension of the array C. LDC >= max(1,M).
WORK (workspace/output) COMPLEX*16 array, dimension (LWORK)
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
LWORK (input) INTEGER
The dimension of the array WORK. If SIDE = 'L', LWORK >=
max(1,N); if SIDE = 'R', LWORK >= max(1,M). For optimum per‐
formance LWORK >= N*NB if SIDE 'L', and LWORK >= M*NB if SIDE =
'R', where NB is the optimal blocksize.
If LWORK = -1, then a workspace query is assumed; the routine
only calculates the optimal size of the WORK array, returns
this value as the first entry of the WORK array, and no error
message related to LWORK is issued by XERBLA.
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
LAPACK version 3.0 15 June 2000 ZUNMLQ(l)