drotmg()

subroutine drotmg	(	double precision	dd1,
		double precision	dd2,
		double precision	dx1,
		double precision	dy1,
		double precision, dimension(5)	dparam )

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

[in,out]	DD1	!> DD1 is DOUBLE PRECISION !>
[in,out]	DD2	!> DD2 is DOUBLE PRECISION !>
[in,out]	DX1	!> DX1 is DOUBLE PRECISION !>
[in]	DY1	!> DY1 is DOUBLE PRECISION !>
[out]	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.