SLARZ - applie a real elementary reflector H to a real M-
by-N matrix C, from either the left or the right
SYNOPSIS
SUBROUTINE SLARZ( SIDE, M, N, L, V, INCV, TAU, C, LDC,
WORK )
CHARACTER SIDE
INTEGER INCV, L, LDC, M, N
REAL TAU
REAL C( LDC, * ), V( * ), WORK( * )
PURPOSE
SLARZ applies a real elementary reflector H to a real M-
by-N matrix C, from either the left or the right. H is
represented in the form
H = I - tau * v * v'
where tau is a real scalar and v is a real vector.
If tau = 0, then H is taken to be the unit matrix.
H is a product of k elementary reflectors as returned by
STZRZF.
ARGUMENTS
SIDE (input) CHARACTER*1
= 'L': form H * C
= 'R': form C * H
M (input) INTEGER
The number of rows of the matrix C.
N (input) INTEGER
The number of columns of the matrix C.
L (input) INTEGER
The number of entries of the vector V containing
the meaningful part of the Householder vectors.
If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L
>= 0.
V (input) REAL array, dimension (1+(L-1)*abs(INCV))
The vector v in the representation of H as
returned by STZRZF. V is not used if TAU = 0.
The increment between elements of v. INCV <> 0.
TAU (input) REAL
The value tau in the representation of H.
C (input/output) REAL array, dimension (LDC,N)
On entry, the M-by-N matrix C. On exit, C is
overwritten by the matrix H * C if SIDE = 'L', or
C * H if SIDE = 'R'.
LDC (input) INTEGER
The leading dimension of the array C. LDC >=
max(1,M).
WORK (workspace) REAL array, dimension
(N) if SIDE = 'L' or (M) if SIDE = 'R'
FURTHER DETAILS
Based on contributions by
A. Petitet, Computer Science Dept., Univ. of Tenn.,
Knoxville, USA
Man(1) output converted with
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