root / src / blas / srot.f @ 10
Historique | Voir | Annoter | Télécharger (1,11 ko)
| 1 |
SUBROUTINE SROT(N,SX,INCX,SY,INCY,C,S) |
|---|---|
| 2 |
* .. Scalar Arguments .. |
| 3 |
REAL C,S |
| 4 |
INTEGER INCX,INCY,N |
| 5 |
* .. |
| 6 |
* .. Array Arguments .. |
| 7 |
REAL SX(*),SY(*) |
| 8 |
* .. |
| 9 |
* |
| 10 |
* Purpose |
| 11 |
* ======= |
| 12 |
* |
| 13 |
* 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 |
REAL STEMP |
| 25 |
INTEGER I,IX,IY |
| 26 |
* .. |
| 27 |
IF (N.LE.0) RETURN |
| 28 |
IF (INCX.EQ.1 .AND. INCY.EQ.1) GO TO 20 |
| 29 |
* |
| 30 |
* code for unequal increments or equal increments not equal |
| 31 |
* to 1 |
| 32 |
* |
| 33 |
IX = 1 |
| 34 |
IY = 1 |
| 35 |
IF (INCX.LT.0) IX = (-N+1)*INCX + 1 |
| 36 |
IF (INCY.LT.0) IY = (-N+1)*INCY + 1 |
| 37 |
DO 10 I = 1,N |
| 38 |
STEMP = C*SX(IX) + S*SY(IY) |
| 39 |
SY(IY) = C*SY(IY) - S*SX(IX) |
| 40 |
SX(IX) = STEMP |
| 41 |
IX = IX + INCX |
| 42 |
IY = IY + INCY |
| 43 |
10 CONTINUE |
| 44 |
RETURN |
| 45 |
* |
| 46 |
* code for both increments equal to 1 |
| 47 |
* |
| 48 |
20 DO 30 I = 1,N |
| 49 |
STEMP = C*SX(I) + S*SY(I) |
| 50 |
SY(I) = C*SY(I) - S*SX(I) |
| 51 |
SX(I) = STEMP |
| 52 |
30 CONTINUE |
| 53 |
RETURN |
| 54 |
END |