zlartg3lapack
Generates a plane rotation so that [ cs sn ] [ f ] [ r ] [ __ ]
Usage
- 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.