SRC/dlartgp.f(3)

NAME
SRC/dlartgp.f

SYNOPSIS

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

Function/Subroutine 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.

Definition at line 94 of file dlartgp.f.

Author

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