NAME

       lartgp - lartgp: generate plane rotation, more accurate than BLAS rot

SYNOPSIS

   Functions
       subroutine dlartgp (f, g, cs, sn, r)
           DLARTGP generates a plane rotation so that the diagonal is nonnegative.
       subroutine slartgp (f, g, cs, sn, r)
           SLARTGP generates a plane rotation so that the diagonal is nonnegative.

Detailed Description

Function Documentation

   subroutine dlartgp (double precision f, double precision g, double precision cs, double
       precision sn, double precision r)
       DLARTGP generates a plane rotation so that the diagonal is nonnegative.

       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.

       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.

   subroutine slartgp (real f, real g, real cs, real sn, real r)
       SLARTGP generates a plane rotation so that the diagonal is nonnegative.

       Purpose:

            SLARTGP 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 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.

            The sign is chosen so that R >= 0.

       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.

Author

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