DLARFG
Purpose
DLARFG generates a real elementary reflector H of order n, such
that
H * ( alpha ) = ( beta ), H**T * H = I.
( 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**T ) ,
( 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.
that
H * ( alpha ) = ( beta ), H**T * H = I.
( 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**T ) ,
( 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
| N |
(input) INTEGER
The order of the elementary reflector.
|
| ALPHA |
(input/output) DOUBLE PRECISION
On entry, the value alpha.
On exit, it is overwritten with the value beta. |
| X |
(input/output) DOUBLE PRECISION array, dimension
(1+(N-2)*abs(INCX))
On entry, the vector x. On exit, it is overwritten with the vector v. |
| INCX |
(input) INTEGER
The increment between elements of X. INCX > 0.
|
| TAU |
(output) DOUBLE PRECISION
The value tau.
|