SRC/dlartgs.f(3)           Library Functions Manual           SRC/dlartgs.f(3)

NAME
       SRC/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.

       Definition at line 89 of file dlartgs.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0                SRC/dlartgs.f(3)