CLARFG(l) ) CLARFG(l)
CLARFG - generate a complex elementary reflector H of order n, such that H' * ( alpha ) =
( beta ), H' * H = I
SUBROUTINE CLARFG( N, ALPHA, X, INCX, TAU )
INTEGER INCX, N
COMPLEX ALPHA, TAU
COMPLEX X( * )
CLARFG generates a complex elementary reflector H of order n, such that H' * ( alpha ) = (
beta ), H' * H = I. ( x ) ( 0 )
where alpha and beta are scalars, with beta real, and x is an (n-1)-element complex vec-
tor. H is represented in the form
H = I - tau * ( 1 ) * ( 1 v' ) ,
( v )
where tau is a complex scalar and v is a complex (n-1)-element vector. Note that H is not
If the elements of x are all zero and alpha is real, then tau = 0 and H is taken to be the
Otherwise 1 <= real(tau) <= 2 and abs(tau-1) <= 1 .
N (input) INTEGER
The order of the elementary reflector.
ALPHA (input/output) COMPLEX
On entry, the value alpha. On exit, it is overwritten with the value beta.
X (input/output) COMPLEX array, dimension
(1+(N-2)*abs(INCX)) On entry, the vector x. On exit, it is overwritten with the
INCX (input) INTEGER
The increment between elements of X. INCX > 0.
TAU (output) COMPLEX
The value tau.
LAPACK version 3.0 15 June 2000 CLARFG(l)