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