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slartgs.f(3)                        LAPACK                        slartgs.f(3)


NAME

       slartgs.f -


SYNOPSIS

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

Function/Subroutine Documentation
   subroutine slartgs (realX, realY, realSIGMA, realCS, realSN)
       SLARTGS generates a plane rotation designed to introduce a bulge in
       implicit QR iteration for the bidiagonal SVD problem.

       Purpose:

            SLARTGS 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 REAL
                     The (1,1) entry of an upper bidiagonal matrix.

           Y

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

           SIGMA

                     SIGMA is REAL
                     The shift.

           CS

                     CS is REAL
                     The cosine of the rotation.

           SN

                     SN is REAL
                     The sine of the rotation.

       Author:
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Date:
           September 2012

       Definition at line 91 of file slartgs.f.

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

Version 3.4.2                   Sat Nov 16 2013                   slartgs.f(3)

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