108 lines
3.2 KiB
Fortran
108 lines
3.2 KiB
Fortran
SUBROUTINE DROTMF (N,DX,INCX,DY,INCY,DPARAM)
|
|
C
|
|
C APPLY THE MODIFIED GIVENS TRANSFORMATION, H, TO THE 2 BY N MATRIX
|
|
C
|
|
C (DX**T) , WHERE **T INDICATES TRANSPOSE. THE ELEMENTS OF DX ARE IN
|
|
C (DY**T)
|
|
C
|
|
C DX(LX+I*INCX), I = 0 TO N-1, WHERE LX = 1 IF INCX .GE. 0, ELSE
|
|
C LX = (-INCX)*N, AND SIMILARLY FOR SY USING LY AND INCY.
|
|
C WITH DPARAM(1)=DFLAG, H HAS ONE OF THE FOLLOWING FORMS..
|
|
C
|
|
C DFLAG=-1.D0 DFLAG=0.D0 DFLAG=1.D0 DFLAG=-2.D0
|
|
C
|
|
C (DH11 DH12) (1.D0 DH12) (DH11 1.D0) (1.D0 0.D0)
|
|
C H=( ) ( ) ( ) ( )
|
|
C (DH21 DH22), (DH21 1.D0), (-1.D0 DH22), (0.D0 1.D0).
|
|
C SEE DROTMG FOR A DESCRIPTION OF DATA STORAGE IN DPARAM.
|
|
C
|
|
DOUBLE PRECISION DFLAG,DH12,DH22,DX,TWO,Z,DH11,DH21,
|
|
1 DPARAM,DY,W,ZERO
|
|
DIMENSION DX(1),DY(1),DPARAM(5)
|
|
DATA ZERO,TWO/0.D0,2.D0/
|
|
C
|
|
DFLAG=DPARAM(1)
|
|
IF(N .LE. 0 .OR.(DFLAG+TWO.EQ.ZERO)) GO TO 140
|
|
IF(.NOT.(INCX.EQ.INCY.AND. INCX .GT.0)) GO TO 70
|
|
C
|
|
NSTEPS=N*INCX
|
|
IF(DFLAG) 50,10,30
|
|
10 CONTINUE
|
|
DH12=DPARAM(4)
|
|
DH21=DPARAM(3)
|
|
DO 20 I=1,NSTEPS,INCX
|
|
W=DX(I)
|
|
Z=DY(I)
|
|
DX(I)=W+Z*DH12
|
|
DY(I)=W*DH21+Z
|
|
20 CONTINUE
|
|
GO TO 140
|
|
30 CONTINUE
|
|
DH11=DPARAM(2)
|
|
DH22=DPARAM(5)
|
|
DO 40 I=1,NSTEPS,INCX
|
|
W=DX(I)
|
|
Z=DY(I)
|
|
DX(I)=W*DH11+Z
|
|
DY(I)=-W+DH22*Z
|
|
40 CONTINUE
|
|
GO TO 140
|
|
50 CONTINUE
|
|
DH11=DPARAM(2)
|
|
DH12=DPARAM(4)
|
|
DH21=DPARAM(3)
|
|
DH22=DPARAM(5)
|
|
DO 60 I=1,NSTEPS,INCX
|
|
W=DX(I)
|
|
Z=DY(I)
|
|
DX(I)=W*DH11+Z*DH12
|
|
DY(I)=W*DH21+Z*DH22
|
|
60 CONTINUE
|
|
GO TO 140
|
|
70 CONTINUE
|
|
KX=1
|
|
KY=1
|
|
IF(INCX .LT. 0) KX=1+(1-N)*INCX
|
|
IF(INCY .LT. 0) KY=1+(1-N)*INCY
|
|
C
|
|
IF(DFLAG)120,80,100
|
|
80 CONTINUE
|
|
DH12=DPARAM(4)
|
|
DH21=DPARAM(3)
|
|
DO 90 I=1,N
|
|
W=DX(KX)
|
|
Z=DY(KY)
|
|
DX(KX)=W+Z*DH12
|
|
DY(KY)=W*DH21+Z
|
|
KX=KX+INCX
|
|
KY=KY+INCY
|
|
90 CONTINUE
|
|
GO TO 140
|
|
100 CONTINUE
|
|
DH11=DPARAM(2)
|
|
DH22=DPARAM(5)
|
|
DO 110 I=1,N
|
|
W=DX(KX)
|
|
Z=DY(KY)
|
|
DX(KX)=W*DH11+Z
|
|
DY(KY)=-W+DH22*Z
|
|
KX=KX+INCX
|
|
KY=KY+INCY
|
|
110 CONTINUE
|
|
GO TO 140
|
|
120 CONTINUE
|
|
DH11=DPARAM(2)
|
|
DH12=DPARAM(4)
|
|
DH21=DPARAM(3)
|
|
DH22=DPARAM(5)
|
|
DO 130 I=1,N
|
|
W=DX(KX)
|
|
Z=DY(KY)
|
|
DX(KX)=W*DH11+Z*DH12
|
|
DY(KY)=W*DH21+Z*DH22
|
|
KX=KX+INCX
|
|
KY=KY+INCY
|
|
130 CONTINUE
|
|
140 CONTINUE
|
|
RETURN
|
|
END
|