SUBROUTINE DROTMG(DD1,DD2,DX1,DY1,DPARAM)
DOUBLE PRECISION DD1,DD2,DX1,DY1
DOUBLE PRECISION DPARAM(5)
DOUBLE PRECISION DFLAG,DH11,DH12,DH21,DH22,DP1,DP2,DQ1,DQ2,DTEMP,
+ DU,GAM,GAMSQ,ONE,RGAMSQ,TWO,ZERO
INTEGER IGO
INTRINSIC DABS
DATA ZERO,ONE,TWO/0.D0,1.D0,2.D0/
DATA GAM,GAMSQ,RGAMSQ/4096.D0,16777216.D0,5.9604645D-8/
IF (.NOT.DD1.LT.ZERO) GO TO 10
GO TO 60
10 CONTINUE
DP2 = DD2*DY1
IF (.NOT.DP2.EQ.ZERO) GO TO 20
DFLAG = -TWO
GO TO 260
20 CONTINUE
DP1 = DD1*DX1
DQ2 = DP2*DY1
DQ1 = DP1*DX1
IF (.NOT.DABS(DQ1).GT.DABS(DQ2)) GO TO 40
DH21 = -DY1/DX1
DH12 = DP2/DP1
DU = ONE - DH12*DH21
IF (.NOT.DU.LE.ZERO) GO TO 30
GO TO 60
30 CONTINUE
DFLAG = ZERO
DD1 = DD1/DU
DD2 = DD2/DU
DX1 = DX1*DU
GO TO 100
40 CONTINUE
IF (.NOT.DQ2.LT.ZERO) GO TO 50
GO TO 60
50 CONTINUE
DFLAG = ONE
DH11 = DP1/DP2
DH22 = DX1/DY1
DU = ONE + DH11*DH22
DTEMP = DD2/DU
DD2 = DD1/DU
DD1 = DTEMP
DX1 = DY1*DU
GO TO 100
60 CONTINUE
DFLAG = -ONE
DH11 = ZERO
DH12 = ZERO
DH21 = ZERO
DH22 = ZERO
DD1 = ZERO
DD2 = ZERO
DX1 = ZERO
GO TO 220
70 CONTINUE
IF (.NOT.DFLAG.GE.ZERO) GO TO 90
IF (.NOT.DFLAG.EQ.ZERO) GO TO 80
DH11 = ONE
DH22 = ONE
DFLAG = -ONE
GO TO 90
80 CONTINUE
DH21 = -ONE
DH12 = ONE
DFLAG = -ONE
90 CONTINUE
GO TO IGO(120,150,180,210)
100 CONTINUE
110 CONTINUE
IF (.NOT.DD1.LE.RGAMSQ) GO TO 130
IF (DD1.EQ.ZERO) GO TO 160
ASSIGN 120 TO IGO
GO TO 70
120 CONTINUE
DD1 = DD1*GAM**2
DX1 = DX1/GAM
DH11 = DH11/GAM
DH12 = DH12/GAM
GO TO 110
130 CONTINUE
140 CONTINUE
IF (.NOT.DD1.GE.GAMSQ) GO TO 160
ASSIGN 150 TO IGO
GO TO 70
150 CONTINUE
DD1 = DD1/GAM**2
DX1 = DX1*GAM
DH11 = DH11*GAM
DH12 = DH12*GAM
GO TO 140
160 CONTINUE
170 CONTINUE
IF (.NOT.DABS(DD2).LE.RGAMSQ) GO TO 190
IF (DD2.EQ.ZERO) GO TO 220
ASSIGN 180 TO IGO
GO TO 70
180 CONTINUE
DD2 = DD2*GAM**2
DH21 = DH21/GAM
DH22 = DH22/GAM
GO TO 170
190 CONTINUE
200 CONTINUE
IF (.NOT.DABS(DD2).GE.GAMSQ) GO TO 220
ASSIGN 210 TO IGO
GO TO 70
210 CONTINUE
DD2 = DD2/GAM**2
DH21 = DH21*GAM
DH22 = DH22*GAM
GO TO 200
220 CONTINUE
IF (DFLAG) 250,230,240
230 CONTINUE
DPARAM(3) = DH21
DPARAM(4) = DH12
GO TO 260
240 CONTINUE
DPARAM(2) = DH11
DPARAM(5) = DH22
GO TO 260
250 CONTINUE
DPARAM(2) = DH11
DPARAM(3) = DH21
DPARAM(4) = DH12
DPARAM(5) = DH22
260 CONTINUE
DPARAM(1) = DFLAG
RETURN
END