NAME
ZLARTG - generates a plane rotation so that [ CS SN ] [ F ] [ R ] [ __ ]
SYNOPSIS
- SUBROUTINE ZLARTG(
-
F, G, CS, SN, R )
- DOUBLE
-
PRECISION CS
- COMPLEX*16
-
F, G, R, SN
PURPOSE
ZLARTG generates a plane rotation so that
[ -SN CS ] [ G ] [ 0 ]
This is a faster version of the BLAS1 routine ZROTG, 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*16
-
The first component of vector to be rotated.
- G (input) COMPLEX*16
-
The second component of vector to be rotated.
- CS (output) DOUBLE PRECISION
-
The cosine of the rotation.
- SN (output) COMPLEX*16
-
The sine of the rotation.
- R (output) COMPLEX*16
-
The nonzero component of the rotated vector.
FURTHER DETAILS
3-5-96 - Modified with a new algorithm by W. Kahan and J. Demmel This version has a few statements commented out for thread safety (machine parameters are computed on each entry). 10 feb 03, SJH.