man slarf (Fonctions bibliothèques) - applie a real elementary reflector H to a real m by n matrix C, from either the left or the right

NAME

SLARF - applie a real elementary reflector H to a real m by n matrix C, from either the left or the right

SYNOPSIS

SUBROUTINE SLARF(
SIDE, M, N, V, INCV, TAU, C, LDC, WORK )
CHARACTER SIDE
INTEGER INCV, LDC, M, N
REAL TAU
REAL C( LDC, * ), V( * ), WORK( * )

PURPOSE

SLARF 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.

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.
V (input) REAL array, dimension
(1 + (M-1)*abs(INCV)) if SIDE = 'L' or (1 + (N-1)*abs(INCV)) if SIDE = 'R' The vector v in the representation of H. V is not used if TAU = 0.
INCV (input) INTEGER
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'