dlartg (l)  Linux Manuals
dlartg: generate a plane rotation so that [ CS SN ]
Command to display dlartg
manual in Linux: $ man l dlartg
NAME
DLARTG  generate a plane rotation so that [ CS SN ]
SYNOPSIS
 SUBROUTINE DLARTG(

F, G, CS, SN, R )

DOUBLE
PRECISION CS, F, G, R, SN
PURPOSE
DLARTG generate a plane rotation so that
[
SN CS ] [ G ] [ 0 ]
This is a slower, more accurate version of the BLAS1 routine DROTG,
with the following other differences:
F and G are unchanged on return.
If G=0, then CS=1 and SN=0.
If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any
floating point operations (saves work in DBDSQR when
there are zeros on the diagonal).
If F exceeds G in magnitude, CS will be positive.
ARGUMENTS
 F (input) DOUBLE PRECISION

The first component of vector to be rotated.
 G (input) DOUBLE PRECISION

The second component of vector to be rotated.
 CS (output) DOUBLE PRECISION

The cosine of the rotation.
 SN (output) DOUBLE PRECISION

The sine of the rotation.
 R (output) DOUBLE PRECISION

The nonzero component of the rotated vector.
This version has a few statements commented out for thread safety
(machine parameters are computed on each entry). 10 feb 03, SJH.
Pages related to dlartg
 dlartg (3)
 dlartv (l)  applies a vector of real plane rotations to elements of the real vectors x and y
 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
 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
 dlarfg (l)  generates a real elementary reflector H of order n, such that H * ( alpha ) = ( beta ), Haq * H = I
 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