dlartgp.f(3)

NAME
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 precisionF, double precisionG, double precisionCS, double precisionSN, double precisionR)

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.

Date:
    September 2012

Definition at line 96 of file dlartgp.f.

Author

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