ZUNMRZ(1) LAPACK routine (version 3.2) ZUNMRZ(1)NAME
ZUNMRZ - overwrites the general complex M-by-N matrix C with SIDE =
'L' SIDE = 'R' TRANS = 'N'
SYNOPSIS
SUBROUTINE ZUNMRZ( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC, WORK,
LWORK, INFO )
CHARACTER SIDE, TRANS
INTEGER INFO, K, L, LDA, LDC, LWORK, M, N
COMPLEX*16 A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
PURPOSE
ZUNMRZ overwrites the general complex M-by-N matrix C with 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(1)H(2) . . . H(k)
as returned by ZTZRZF. 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.
L (input) INTEGER
The number of columns of the matrix A containing the meaningful
part of the Householder reflectors. If SIDE = 'L', M >= L >=
0, if SIDE = 'R', N >= L >= 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 ZTZRZF in the last 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 ZTZRZF.
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 (MAX(1,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
FURTHER DETAILS
Based on contributions by
A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
LAPACK routine (version 3.2) November 2008 ZUNMRZ(1)