drotmg.f(3)

NAME
drotmg.f -

SYNOPSIS

  Functions/Subroutines
subroutine drotmg (DD1, DD2, DX1, DY1, DPARAM)
DROTMG

Function/Subroutine Documentation

  subroutine drotmg (double precisionDD1, double precisionDD2, double precisionDX1, double precisionDY1, double precision, dimension(5)DPARAM)

Purpose:

        CONSTRUCT THE MODIFIED GIVENS TRANSFORMATION MATRIX H WHICH ZEROS
        THE SECOND COMPONENT OF THE 2-VECTOR  (DSQRT(DD1)*DX1,DSQRT(DD2)*>    DY2)**T.
        WITH DPARAM(1)=DFLAG, H HAS ONE OF THE FOLLOWING FORMS..
        DFLAG=-1.D0     DFLAG=0.D0        DFLAG=1.D0     DFLAG=-2.D0
          (DH11  DH12)    (1.D0  DH12)    (DH11  1.D0)    (1.D0  0.D0)
        H=(          )    (          )    (          )    (          )
          (DH21  DH22),   (DH21  1.D0),   (-1.D0 DH22),   (0.D0  1.D0).
        LOCATIONS 2-4 OF DPARAM CONTAIN DH11, DH21, DH12, AND DH22
        RESPECTIVELY. (VALUES OF 1.D0, -1.D0, OR 0.D0 IMPLIED BY THE
        VALUE OF DPARAM(1) ARE NOT STORED IN DPARAM.)
        THE VALUES OF GAMSQ AND RGAMSQ SET IN THE DATA STATEMENT MAY BE
        INEXACT.  THIS IS OK AS THEY ARE ONLY USED FOR TESTING THE SIZE
        OF DD1 AND DD2.  ALL ACTUAL SCALING OF DATA IS DONE USING GAM.

Parameters:
    DD1

              DD1 is DOUBLE PRECISION

    DD2

              DD2 is DOUBLE PRECISION

    DX1

              DX1 is DOUBLE PRECISION

    DY1

              DY1 is DOUBLE PRECISION

    DPARAM

              DPARAM is DOUBLE PRECISION array, dimension 5
         DPARAM(1)=DFLAG
         DPARAM(2)=DH11
         DPARAM(3)=DH21
         DPARAM(4)=DH12
         DPARAM(5)=DH22

Author:
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Date:
    November 2011

Definition at line 91 of file drotmg.f.

Author

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