1 SUBROUTINE SSWAP(N,SX,INCX,SY,INCY)
2 * .. Scalar Arguments ..
3 INTEGER INCX,INCY,N
4 * ..
5 * .. Array Arguments ..
6 REAL SX(*),SY(*)
7 * ..
8 *
9 * Purpose
10 * =======
11 *
12 * interchanges two vectors.
13 * uses unrolled loops for increments equal to 1.
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 REAL STEMP
25 INTEGER I,IX,IY,M,MP1
26 * ..
27 * .. Intrinsic Functions ..
28 INTRINSIC MOD
29 * ..
30 IF (N.LE.0) RETURN
31 IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
32 *
33 * code for both increments equal to 1
34 *
35 *
36 * clean-up loop
37 *
38 M = MOD(N,3)
39 IF (M.NE.0) THEN
40 DO I = 1,M
41 STEMP = SX(I)
42 SX(I) = SY(I)
43 SY(I) = STEMP
44 END DO
45 IF (N.LT.3) RETURN
46 END IF
47 MP1 = M + 1
48 DO I = MP1,N,3
49 STEMP = SX(I)
50 SX(I) = SY(I)
51 SY(I) = STEMP
52 STEMP = SX(I+1)
53 SX(I+1) = SY(I+1)
54 SY(I+1) = STEMP
55 STEMP = SX(I+2)
56 SX(I+2) = SY(I+2)
57 SY(I+2) = STEMP
58 END DO
59 ELSE
60 *
61 * code for unequal increments or equal increments not equal
62 * to 1
63 *
64 IX = 1
65 IY = 1
66 IF (INCX.LT.0) IX = (-N+1)*INCX + 1
67 IF (INCY.LT.0) IY = (-N+1)*INCY + 1
68 DO I = 1,N
69 STEMP = SX(IX)
70 SX(IX) = SY(IY)
71 SY(IY) = STEMP
72 IX = IX + INCX
73 IY = IY + INCY
74 END DO
75 END IF
76 RETURN
77 END
2 * .. Scalar Arguments ..
3 INTEGER INCX,INCY,N
4 * ..
5 * .. Array Arguments ..
6 REAL SX(*),SY(*)
7 * ..
8 *
9 * Purpose
10 * =======
11 *
12 * interchanges two vectors.
13 * uses unrolled loops for increments equal to 1.
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 REAL STEMP
25 INTEGER I,IX,IY,M,MP1
26 * ..
27 * .. Intrinsic Functions ..
28 INTRINSIC MOD
29 * ..
30 IF (N.LE.0) RETURN
31 IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
32 *
33 * code for both increments equal to 1
34 *
35 *
36 * clean-up loop
37 *
38 M = MOD(N,3)
39 IF (M.NE.0) THEN
40 DO I = 1,M
41 STEMP = SX(I)
42 SX(I) = SY(I)
43 SY(I) = STEMP
44 END DO
45 IF (N.LT.3) RETURN
46 END IF
47 MP1 = M + 1
48 DO I = MP1,N,3
49 STEMP = SX(I)
50 SX(I) = SY(I)
51 SY(I) = STEMP
52 STEMP = SX(I+1)
53 SX(I+1) = SY(I+1)
54 SY(I+1) = STEMP
55 STEMP = SX(I+2)
56 SX(I+2) = SY(I+2)
57 SY(I+2) = STEMP
58 END DO
59 ELSE
60 *
61 * code for unequal increments or equal increments not equal
62 * to 1
63 *
64 IX = 1
65 IY = 1
66 IF (INCX.LT.0) IX = (-N+1)*INCX + 1
67 IF (INCY.LT.0) IY = (-N+1)*INCY + 1
68 DO I = 1,N
69 STEMP = SX(IX)
70 SX(IX) = SY(IY)
71 SY(IY) = STEMP
72 IX = IX + INCX
73 IY = IY + INCY
74 END DO
75 END IF
76 RETURN
77 END