1 SUBROUTINE DROT(N,DX,INCX,DY,INCY,C,S)
2 * .. Scalar Arguments ..
3 DOUBLE PRECISION C,S
4 INTEGER INCX,INCY,N
5 * ..
6 * .. Array Arguments ..
7 DOUBLE PRECISION DX(*),DY(*)
8 * ..
9 *
10 * Purpose
11 * =======
12 *
13 * DROT applies a plane rotation.
14 *
15 * Further Details
16 * ===============
17 *
18 * jack dongarra, linpack, 3/11/78.
19 * modified 12/3/93, array(1) declarations changed to array(*)
20 *
21 * =====================================================================
22 *
23 * .. Local Scalars ..
24 DOUBLE PRECISION DTEMP
25 INTEGER I,IX,IY
26 * ..
27 IF (N.LE.0) RETURN
28 IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
29 *
30 * code for both increments equal to 1
31 *
32 DO I = 1,N
33 DTEMP = C*DX(I) + S*DY(I)
34 DY(I) = C*DY(I) - S*DX(I)
35 DX(I) = DTEMP
36 END DO
37 ELSE
38 *
39 * code for unequal increments or equal increments not equal
40 * to 1
41 *
42 IX = 1
43 IY = 1
44 IF (INCX.LT.0) IX = (-N+1)*INCX + 1
45 IF (INCY.LT.0) IY = (-N+1)*INCY + 1
46 DO I = 1,N
47 DTEMP = C*DX(IX) + S*DY(IY)
48 DY(IY) = C*DY(IY) - S*DX(IX)
49 DX(IX) = DTEMP
50 IX = IX + INCX
51 IY = IY + INCY
52 END DO
53 END IF
54 RETURN
55 END
2 * .. Scalar Arguments ..
3 DOUBLE PRECISION C,S
4 INTEGER INCX,INCY,N
5 * ..
6 * .. Array Arguments ..
7 DOUBLE PRECISION DX(*),DY(*)
8 * ..
9 *
10 * Purpose
11 * =======
12 *
13 * DROT applies a plane rotation.
14 *
15 * Further Details
16 * ===============
17 *
18 * jack dongarra, linpack, 3/11/78.
19 * modified 12/3/93, array(1) declarations changed to array(*)
20 *
21 * =====================================================================
22 *
23 * .. Local Scalars ..
24 DOUBLE PRECISION DTEMP
25 INTEGER I,IX,IY
26 * ..
27 IF (N.LE.0) RETURN
28 IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
29 *
30 * code for both increments equal to 1
31 *
32 DO I = 1,N
33 DTEMP = C*DX(I) + S*DY(I)
34 DY(I) = C*DY(I) - S*DX(I)
35 DX(I) = DTEMP
36 END DO
37 ELSE
38 *
39 * code for unequal increments or equal increments not equal
40 * to 1
41 *
42 IX = 1
43 IY = 1
44 IF (INCX.LT.0) IX = (-N+1)*INCX + 1
45 IF (INCY.LT.0) IY = (-N+1)*INCY + 1
46 DO I = 1,N
47 DTEMP = C*DX(IX) + S*DY(IY)
48 DY(IY) = C*DY(IY) - S*DX(IX)
49 DX(IX) = DTEMP
50 IX = IX + INCX
51 IY = IY + INCY
52 END DO
53 END IF
54 RETURN
55 END