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.

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.

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

September 2012