slarfg (l) - Linux Manuals
slarfg: generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
Command to display slarfg
manual in Linux: $ man l slarfg
NAME
SLARFG - generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
SYNOPSIS
- SUBROUTINE SLARFG(
-
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 vaq ) ,
( 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) REAL
-
On entry, the value alpha.
On exit, it is overwritten with the value beta.
- X (input/output) REAL 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) REAL
-
The value tau.
Pages related to slarfg
- slarfg (3)
- slarf (l) - applies a real elementary reflector H to a real m by n matrix C, from either the left or the right
- slarfb (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
- slarfp (l) - generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
- slarft (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
- slarfx (l) - applies a real elementary reflector H to a real m by n matrix C, from either the left or the right
- slar1v (l) - computes the (scaled) r-th column of the inverse of the sumbmatrix in rows B1 through BN of the tridiagonal matrix L D L^T - sigma I
- slar2v (l) - applies a vector of real plane rotations from both sides to a sequence of 2-by-2 real symmetric matrices, defined by the elements of the vectors x, y and z
- slargv (l) - generates a vector of real plane rotations, determined by elements of the real vectors x and y
- slarnv (l) - returns a vector of n random real numbers from a uniform or normal distribution