ZUNMTR(1) LAPACK routine (version 3.2) ZUNMTR(1)NAME
ZUNMTR - overwrites the general complex M-by-N matrix C with SIDE =
'L' SIDE = 'R' TRANS = 'N'
SYNOPSIS
SUBROUTINE ZUNMTR( SIDE, UPLO, TRANS, M, N, A, LDA, TAU, C, LDC, WORK,
LWORK, INFO )
CHARACTER SIDE, TRANS, UPLO
INTEGER INFO, LDA, LDC, LWORK, M, N
COMPLEX*16 A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
PURPOSE
ZUNMTR 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 of order nq, with nq = m if SIDE =
'L' and nq = n if SIDE = 'R'. Q is defined as the product of nq-1 ele‐
mentary reflectors, as returned by ZHETRD:
if UPLO = 'U', Q = H(nq-1) . . . H(2)H(1);
if UPLO = 'L', Q = H(1)H(2) . . . H(nq-1).
ARGUMENTS
SIDE (input) CHARACTER*1
= 'L': apply Q or Q**H from the Left;
= 'R': apply Q or Q**H from the Right.
UPLO (input) CHARACTER*1
= 'U': Upper triangle of A contains elementary reflectors from
ZHETRD; = 'L': Lower triangle of A contains elementary reflec‐
tors from ZHETRD.
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.
A (input) COMPLEX*16 array, dimension
(LDA,M) if SIDE = 'L' (LDA,N) if SIDE = 'R' The vectors which
define the elementary reflectors, as returned by ZHETRD.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,M) if SIDE
= 'L'; LDA >= max(1,N) if SIDE = 'R'.
TAU (input) COMPLEX*16 array, dimension
(M-1) if SIDE = 'L' (N-1) if SIDE = 'R' TAU(i) must contain the
scalar factor of the elementary reflector H(i), as returned by
ZHETRD.
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
LAPACK routine (version 3.2) November 2008 ZUNMTR(1)
