dlartg.f man page

dlartg.f —

Synopsis

Functions/Subroutines

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

Function/Subroutine Documentation

subroutine dlartg (double precisionF, double precisionG, double precisionCS, double precisionSN, double precisionR)

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

Purpose:

DLARTG 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 DROTG,
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 DBDSQR when
      there are zeros on the diagonal).

If F exceeds G in magnitude, CS will be positive.

Parameters:

F

F is DOUBLE PRECISION
The first component of vector to be rotated.

G

G is DOUBLE PRECISION
The second component of vector to be rotated.

CS

CS is DOUBLE PRECISION
The cosine of the rotation.

SN

SN is DOUBLE PRECISION
The sine of the rotation.

R

        R is DOUBLE PRECISION
        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 dlartg.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

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

Sat Nov 16 2013 Version 3.4.2 LAPACK