man clartg (Fonctions bibliothèques) - generate a plane rotation so that [ CS SN ] [ F ] [ R ] [ __ ]

NAME

CLARTG - generate a plane rotation so that [ CS SN ] [ F ] [ R ] [ __ ]

SYNOPSIS

SUBROUTINE CLARTG(
F, G, CS, SN, R )
REAL CS
COMPLEX F, G, R, SN

PURPOSE

CLARTG generates a plane rotation so that [ CS SN ] [ F ] [ R ] [ __ ] . [ ] = [ ] where CS**2 + |SN|**2 = 1. [ -SN CS ] [ G ] [ 0 ]

This is a faster version of the BLAS1 routine CROTG, except for the following differences:

F and G are unchanged on return.

If G=0, then CS=1 and SN=0.

If F=0, then CS=0 and SN is chosen so that R is real.

ARGUMENTS

F (input) COMPLEX
The first component of vector to be rotated.
G (input) COMPLEX
The second component of vector to be rotated.
CS (output) REAL
The cosine of the rotation.
SN (output) COMPLEX
The sine of the rotation.
R (output) COMPLEX
The nonzero component of the rotated vector.

FURTHER DETAILS

3-5-96 - Modified with a new algorithm by W. Kahan and J. Demmel