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