slartg(3)
NAME
SLARTG - generate a plane rotation so that [ CS SN ]
SYNOPSIS
SUBROUTINE SLARTG( F, G, CS, SN, R )
REAL CS, F, G, R, SN
PURPOSE
- SLARTG generate a plane rotation so that [ CS SN ] . [ F ]
- = [ R ] where CS**2 + SN**2 = 1. [ -SN CS ] [ G ] [
- 0 ]
- This is a slower, more accurate version of the BLAS1 rou
- tine SROTG, 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 SBDSQR when
there are zeros on the diagonal). - If F exceeds G in magnitude, CS will be positive.
ARGUMENTS
- F (input) REAL
- The first component of vector to be rotated.
- G (input) REAL
- The second component of vector to be rotated.
- CS (output) REAL
- The cosine of the rotation.
- SN (output) REAL
- The sine of the rotation.
- R (output) REAL
- The nonzero component of the rotated vector.
- LAPACK version 3.0 15 June 2000