root / src / blas / csrot.f @ 7
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| 1 | 1 | equemene | SUBROUTINE CSROT( N, CX, INCX, CY, INCY, C, S ) |
|---|---|---|---|
| 2 | 1 | equemene | * |
| 3 | 1 | equemene | * .. Scalar Arguments .. |
| 4 | 1 | equemene | INTEGER INCX, INCY, N |
| 5 | 1 | equemene | REAL C, S |
| 6 | 1 | equemene | * .. |
| 7 | 1 | equemene | * .. Array Arguments .. |
| 8 | 1 | equemene | COMPLEX CX( * ), CY( * ) |
| 9 | 1 | equemene | * .. |
| 10 | 1 | equemene | * |
| 11 | 1 | equemene | * Purpose |
| 12 | 1 | equemene | * ======= |
| 13 | 1 | equemene | * |
| 14 | 1 | equemene | * Applies a plane rotation, where the cos and sin (c and s) are real |
| 15 | 1 | equemene | * and the vectors cx and cy are complex. |
| 16 | 1 | equemene | * jack dongarra, linpack, 3/11/78. |
| 17 | 1 | equemene | * |
| 18 | 1 | equemene | * Arguments |
| 19 | 1 | equemene | * ========== |
| 20 | 1 | equemene | * |
| 21 | 1 | equemene | * N (input) INTEGER |
| 22 | 1 | equemene | * On entry, N specifies the order of the vectors cx and cy. |
| 23 | 1 | equemene | * N must be at least zero. |
| 24 | 1 | equemene | * Unchanged on exit. |
| 25 | 1 | equemene | * |
| 26 | 1 | equemene | * CX (input) COMPLEX array, dimension at least |
| 27 | 1 | equemene | * ( 1 + ( N - 1 )*abs( INCX ) ). |
| 28 | 1 | equemene | * Before entry, the incremented array CX must contain the n |
| 29 | 1 | equemene | * element vector cx. On exit, CX is overwritten by the updated |
| 30 | 1 | equemene | * vector cx. |
| 31 | 1 | equemene | * |
| 32 | 1 | equemene | * INCX (input) INTEGER |
| 33 | 1 | equemene | * On entry, INCX specifies the increment for the elements of |
| 34 | 1 | equemene | * CX. INCX must not be zero. |
| 35 | 1 | equemene | * Unchanged on exit. |
| 36 | 1 | equemene | * |
| 37 | 1 | equemene | * CY (input) COMPLEX array, dimension at least |
| 38 | 1 | equemene | * ( 1 + ( N - 1 )*abs( INCY ) ). |
| 39 | 1 | equemene | * Before entry, the incremented array CY must contain the n |
| 40 | 1 | equemene | * element vector cy. On exit, CY is overwritten by the updated |
| 41 | 1 | equemene | * vector cy. |
| 42 | 1 | equemene | * |
| 43 | 1 | equemene | * INCY (input) INTEGER |
| 44 | 1 | equemene | * On entry, INCY specifies the increment for the elements of |
| 45 | 1 | equemene | * CY. INCY must not be zero. |
| 46 | 1 | equemene | * Unchanged on exit. |
| 47 | 1 | equemene | * |
| 48 | 1 | equemene | * C (input) REAL |
| 49 | 1 | equemene | * On entry, C specifies the cosine, cos. |
| 50 | 1 | equemene | * Unchanged on exit. |
| 51 | 1 | equemene | * |
| 52 | 1 | equemene | * S (input) REAL |
| 53 | 1 | equemene | * On entry, S specifies the sine, sin. |
| 54 | 1 | equemene | * Unchanged on exit. |
| 55 | 1 | equemene | * |
| 56 | 1 | equemene | * ===================================================================== |
| 57 | 1 | equemene | * |
| 58 | 1 | equemene | * .. Local Scalars .. |
| 59 | 1 | equemene | INTEGER I, IX, IY |
| 60 | 1 | equemene | COMPLEX CTEMP |
| 61 | 1 | equemene | * .. |
| 62 | 1 | equemene | * .. Executable Statements .. |
| 63 | 1 | equemene | * |
| 64 | 1 | equemene | IF( N.LE.0 ) |
| 65 | 1 | equemene | $ RETURN |
| 66 | 1 | equemene | IF( INCX.EQ.1 .AND. INCY.EQ.1 ) |
| 67 | 1 | equemene | $ GO TO 20 |
| 68 | 1 | equemene | * |
| 69 | 1 | equemene | * code for unequal increments or equal increments not equal |
| 70 | 1 | equemene | * to 1 |
| 71 | 1 | equemene | * |
| 72 | 1 | equemene | IX = 1 |
| 73 | 1 | equemene | IY = 1 |
| 74 | 1 | equemene | IF( INCX.LT.0 ) |
| 75 | 1 | equemene | $ IX = ( -N+1 )*INCX + 1 |
| 76 | 1 | equemene | IF( INCY.LT.0 ) |
| 77 | 1 | equemene | $ IY = ( -N+1 )*INCY + 1 |
| 78 | 1 | equemene | DO 10 I = 1, N |
| 79 | 1 | equemene | CTEMP = C*CX( IX ) + S*CY( IY ) |
| 80 | 1 | equemene | CY( IY ) = C*CY( IY ) - S*CX( IX ) |
| 81 | 1 | equemene | CX( IX ) = CTEMP |
| 82 | 1 | equemene | IX = IX + INCX |
| 83 | 1 | equemene | IY = IY + INCY |
| 84 | 1 | equemene | 10 CONTINUE |
| 85 | 1 | equemene | RETURN |
| 86 | 1 | equemene | * |
| 87 | 1 | equemene | * code for both increments equal to 1 |
| 88 | 1 | equemene | * |
| 89 | 1 | equemene | 20 DO 30 I = 1, N |
| 90 | 1 | equemene | CTEMP = C*CX( I ) + S*CY( I ) |
| 91 | 1 | equemene | CY( I ) = C*CY( I ) - S*CX( I ) |
| 92 | 1 | equemene | CX( I ) = CTEMP |
| 93 | 1 | equemene | 30 CONTINUE |
| 94 | 1 | equemene | RETURN |
| 95 | 1 | equemene | END |