1ZLARZ(1)                 LAPACK routine (version 3.2)                 ZLARZ(1)
2
3
4

NAME

6       ZLARZ  -  applies  a complex elementary reflector H to a complex M-by-N
7       matrix C, from either the left or the right
8

SYNOPSIS

10       SUBROUTINE ZLARZ( SIDE, M, N, L, V, INCV, TAU, C, LDC, WORK )
11
12           CHARACTER     SIDE
13
14           INTEGER       INCV, L, LDC, M, N
15
16           COMPLEX*16    TAU
17
18           COMPLEX*16    C( LDC, * ), V( * ), WORK( * )
19

PURPOSE

21       ZLARZ applies a complex elementary reflector  H  to  a  complex  M-by-N
22       matrix  C,  from  either the left or the right. H is represented in the
23       form
24             H = I - tau * v * v'
25       where tau is a complex scalar and v is a complex vector.
26       If tau = 0, then H is taken to be the unit matrix.
27       To apply H' (the conjugate transpose of H), supply  conjg(tau)  instead
28       tau.
29       H is a product of k elementary reflectors as returned by ZTZRZF.
30

ARGUMENTS

32       SIDE    (input) CHARACTER*1
33               = 'L': form  H * C
34               = 'R': form  C * H
35
36       M       (input) INTEGER
37               The number of rows of the matrix C.
38
39       N       (input) INTEGER
40               The number of columns of the matrix C.
41
42       L       (input) INTEGER
43               The number of entries of the vector V containing the meaningful
44               part of the Householder vectors.  If SIDE = 'L', M >= L  >=  0,
45               if SIDE = 'R', N >= L >= 0.
46
47       V       (input) COMPLEX*16 array, dimension (1+(L-1)*abs(INCV))
48               The  vector v in the representation of H as returned by ZTZRZF.
49               V is not used if TAU = 0.
50
51       INCV    (input) INTEGER
52               The increment between elements of v. INCV <> 0.
53
54       TAU     (input) COMPLEX*16
55               The value tau in the representation of H.
56
57       C       (input/output) COMPLEX*16 array, dimension (LDC,N)
58               On entry, the M-by-N matrix C.  On exit, C  is  overwritten  by
59               the matrix H * C if SIDE = 'L', or C * H if SIDE = 'R'.
60
61       LDC     (input) INTEGER
62               The leading dimension of the array C. LDC >= max(1,M).
63
64       WORK    (workspace) COMPLEX*16 array, dimension
65               (N) if SIDE = 'L' or (M) if SIDE = 'R'
66

FURTHER DETAILS

68       Based on contributions by
69         A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
70
71
72
73 LAPACK routine (version 3.2)    November 2008                        ZLARZ(1)
Impressum