drotmg.f - Man Page

subroutine drotmg (dd1, dd2, dx1, dy1, dparam)
DROTMG

DROTMG

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.

Definition at line 89 of file drotmg.f.