SRC/slartgs.f(3)

NAME
SRC/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 (real x, real y, real sigma, real cs, real sn)

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.

Definition at line 89 of file slartgs.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.