dlarfg (l)  Linux Manuals
dlarfg: generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
Command to display dlarfg
manual in Linux: $ man l dlarfg
NAME
DLARFG  generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
SYNOPSIS
 SUBROUTINE DLARFG(

N, ALPHA, X, INCX, TAU )

INTEGER
INCX, N

DOUBLE
PRECISION ALPHA, TAU

DOUBLE
PRECISION X( * )
PURPOSE
DLARFG generates a real elementary reflector H of order n, such
that
( x ) ( 0 )
where alpha and beta are scalars, and x is an (n1)element real
vector. H is represented in the form
H = I  tau * ( 1 ) * ( 1 vaq ) ,
( v )
where tau is a real scalar and v is a real (n1)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+(N2)*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.
Pages related to dlarfg
 dlarfg (3)
 dlarf (l)  applies a real elementary reflector H to a real m by n matrix C, from either the left or the right
 dlarfb (l)  applies a real block reflector H or its transpose Haq to a real m by n matrix C, from either the left or the right
 dlarfp (l)  generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
 dlarft (l)  forms the triangular factor T of a real block reflector H of order n, which is defined as a product of k elementary reflectors
 dlarfx (l)  applies a real elementary reflector H to a real m by n matrix C, from either the left or the right
 dlar1v (l)  computes the (scaled) rth column of the inverse of the sumbmatrix in rows B1 through BN of the tridiagonal matrix L D L^T  sigma I
 dlar2v (l)  applies a vector of real plane rotations from both sides to a sequence of 2by2 real symmetric matrices, defined by the elements of the vectors x, y and z
 dlargv (l)  generates a vector of real plane rotations, determined by elements of the real vectors x and y
 dlarnv (l)  returns a vector of n random real numbers from a uniform or normal distribution