Scroll to navigation

SLARFG(1) LAPACK auxiliary routine (version 3.2) SLARFG(1)

NAME

SLARFG - generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), H' * H = I

SYNOPSIS

N, ALPHA, X, INCX, TAU )

INTEGER INCX, N REAL ALPHA, TAU REAL X( * )

PURPOSE

SLARFG generates a real elementary reflector H of order n, such that
( x ) ( 0 )
where alpha and beta are scalars, and x is an (n-1)-element real vector. H is represented in the form
H = I - tau * ( 1 ) * ( 1 v' ) ,
( v )
where tau is a real scalar and v is a real (n-1)-element
vector.
If the elements of x are all zero, then tau = 0 and H is taken to be the unit matrix.
Otherwise 1 <= tau <= 2.

ARGUMENTS

The order of the elementary reflector.
On entry, the value alpha. On exit, it is overwritten with the value beta.
(1+(N-2)*abs(INCX)) On entry, the vector x. On exit, it is overwritten with the vector v.
The increment between elements of X. INCX > 0.
The value tau.
November 2008 LAPACK auxiliary routine (version 3.2)