DLARTGP(3)     LAPACK routine of NEC Numeric Library Collection     DLARTGP(3)



NAME
       DLARTGP

SYNOPSIS
       SUBROUTINE DLARTGP (F, G, CS, SN, R)



PURPOSE
            DLARTGP generates 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 Level 1 BLAS 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.

            The sign is chosen so that R >= 0.




ARGUMENTS
           F         (input)
                     F is DOUBLE PRECISION
                     The first component of vector to be rotated.

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

           CS        (output)
                     CS is DOUBLE PRECISION
                     The cosine of the rotation.

           SN        (output)
                     SN is DOUBLE PRECISION
                     The sine of the rotation.

           R         (output)
                     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.



LAPACK routine                  31 October 2017                     DLARTGP(3)