slartg.f man page

slartg.f —

Synopsis

Functions/Subroutines

subroutine slartg (F, G, CS, SN, R)
SLARTG generates a plane rotation with real cosine and real sine.

Function/Subroutine Documentation

subroutine slartg (realF, realG, realCS, realSN, realR)

SLARTG generates a plane rotation with real cosine and real sine.

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 routine 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.

Parameters:

F

F is REAL
The first component of vector to be rotated.

G

G is REAL
The second component of vector to be rotated.

CS

CS is REAL
The cosine of the rotation.

SN

SN is REAL
The sine of the rotation.

R

        R is REAL
        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.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 98 of file slartg.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

slartg(3) is an alias of slartg.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK