NAME

       dlartgs.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dlartgs (X, Y, SIGMA, CS, SN)
           DLARTGS generates a plane rotation designed to introduce a bulge in implicit QR iteration for the
           bidiagonal SVD problem.

Function/Subroutine Documentation

   subroutine dlartgs (double precision X, double precision Y, double precision SIGMA, double precision CS,
       double precision SN)
       DLARTGS generates a plane rotation designed to introduce a bulge in implicit QR iteration for the
       bidiagonal SVD problem.

       Purpose:

            DLARTGS generates a plane rotation designed to introduce a bulge in
            Golub-Reinsch-style implicit QR iteration for the bidiagonal SVD
            problem. X and Y are the top-row entries, and SIGMA is the shift.
            The computed CS and SN define a plane rotation satisfying

               [  CS  SN  ]  .  [ X^2 - SIGMA ]  =  [ R ],
               [ -SN  CS  ]     [    X * Y    ]     [ 0 ]

            with R nonnegative.  If X^2 - SIGMA and X * Y are 0, then the
            rotation is by PI/2.

       Parameters:
           X

                     X is DOUBLE PRECISION
                     The (1,1) entry of an upper bidiagonal matrix.

           Y

                     Y is DOUBLE PRECISION
                     The (1,2) entry of an upper bidiagonal matrix.

           SIGMA

                     SIGMA is DOUBLE PRECISION
                     The shift.

           CS

                     CS is DOUBLE PRECISION
                     The cosine of the rotation.

           SN

                     SN is DOUBLE PRECISION
                     The sine of the rotation.

       Author:
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Date:
           September 2012

Author

       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.6.0                                    Sun Jan 17 2016                                    dlartgs.f(3)