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| 1 | 1 | equemene | DOUBLE PRECISION FUNCTION DSDOT(N,SX,INCX,SY,INCY) |
|---|---|---|---|
| 2 | 1 | equemene | * .. Scalar Arguments .. |
| 3 | 1 | equemene | INTEGER INCX,INCY,N |
| 4 | 1 | equemene | * .. |
| 5 | 1 | equemene | * .. Array Arguments .. |
| 6 | 1 | equemene | REAL SX(*),SY(*) |
| 7 | 1 | equemene | * .. |
| 8 | 1 | equemene | * |
| 9 | 1 | equemene | * AUTHORS |
| 10 | 1 | equemene | * ======= |
| 11 | 1 | equemene | * Lawson, C. L., (JPL), Hanson, R. J., (SNLA), |
| 12 | 1 | equemene | * Kincaid, D. R., (U. of Texas), Krogh, F. T., (JPL) |
| 13 | 1 | equemene | * |
| 14 | 1 | equemene | * Purpose |
| 15 | 1 | equemene | * ======= |
| 16 | 1 | equemene | * Compute the inner product of two vectors with extended |
| 17 | 1 | equemene | * precision accumulation and result. |
| 18 | 1 | equemene | * |
| 19 | 1 | equemene | * Returns D.P. dot product accumulated in D.P., for S.P. SX and SY |
| 20 | 1 | equemene | * DSDOT = sum for I = 0 to N-1 of SX(LX+I*INCX) * SY(LY+I*INCY), |
| 21 | 1 | equemene | * where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is |
| 22 | 1 | equemene | * defined in a similar way using INCY. |
| 23 | 1 | equemene | * |
| 24 | 1 | equemene | * Arguments |
| 25 | 1 | equemene | * ========= |
| 26 | 1 | equemene | * |
| 27 | 1 | equemene | * N (input) INTEGER |
| 28 | 1 | equemene | * number of elements in input vector(s) |
| 29 | 1 | equemene | * |
| 30 | 1 | equemene | * SX (input) REAL array, dimension(N) |
| 31 | 1 | equemene | * single precision vector with N elements |
| 32 | 1 | equemene | * |
| 33 | 1 | equemene | * INCX (input) INTEGER |
| 34 | 1 | equemene | * storage spacing between elements of SX |
| 35 | 1 | equemene | * |
| 36 | 1 | equemene | * SY (input) REAL array, dimension(N) |
| 37 | 1 | equemene | * single precision vector with N elements |
| 38 | 1 | equemene | * |
| 39 | 1 | equemene | * INCY (input) INTEGER |
| 40 | 1 | equemene | * storage spacing between elements of SY |
| 41 | 1 | equemene | * |
| 42 | 1 | equemene | * DSDOT (output) DOUBLE PRECISION |
| 43 | 1 | equemene | * DSDOT double precision dot product (zero if N.LE.0) |
| 44 | 1 | equemene | * |
| 45 | 1 | equemene | * REFERENCES |
| 46 | 1 | equemene | * ========== |
| 47 | 1 | equemene | * |
| 48 | 1 | equemene | * C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T. |
| 49 | 1 | equemene | * Krogh, Basic linear algebra subprograms for Fortran |
| 50 | 1 | equemene | * usage, Algorithm No. 539, Transactions on Mathematical |
| 51 | 1 | equemene | * Software 5, 3 (September 1979), pp. 308-323. |
| 52 | 1 | equemene | * |
| 53 | 1 | equemene | * REVISION HISTORY (YYMMDD) |
| 54 | 1 | equemene | * ========================== |
| 55 | 1 | equemene | * |
| 56 | 1 | equemene | * 791001 DATE WRITTEN |
| 57 | 1 | equemene | * 890831 Modified array declarations. (WRB) |
| 58 | 1 | equemene | * 890831 REVISION DATE from Version 3.2 |
| 59 | 1 | equemene | * 891214 Prologue converted to Version 4.0 format. (BAB) |
| 60 | 1 | equemene | * 920310 Corrected definition of LX in DESCRIPTION. (WRB) |
| 61 | 1 | equemene | * 920501 Reformatted the REFERENCES section. (WRB) |
| 62 | 1 | equemene | * 070118 Reformat to LAPACK style (JL) |
| 63 | 1 | equemene | * |
| 64 | 1 | equemene | * ===================================================================== |
| 65 | 1 | equemene | * |
| 66 | 1 | equemene | * .. Local Scalars .. |
| 67 | 1 | equemene | INTEGER I,KX,KY,NS |
| 68 | 1 | equemene | * .. |
| 69 | 1 | equemene | * .. Intrinsic Functions .. |
| 70 | 1 | equemene | INTRINSIC DBLE |
| 71 | 1 | equemene | * .. |
| 72 | 1 | equemene | DSDOT = 0.0D0 |
| 73 | 1 | equemene | IF (N.LE.0) RETURN |
| 74 | 1 | equemene | IF (INCX.EQ.INCY .AND. INCX.GT.0) GO TO 20 |
| 75 | 1 | equemene | * |
| 76 | 1 | equemene | * Code for unequal or nonpositive increments. |
| 77 | 1 | equemene | * |
| 78 | 1 | equemene | KX = 1 |
| 79 | 1 | equemene | KY = 1 |
| 80 | 1 | equemene | IF (INCX.LT.0) KX = 1 + (1-N)*INCX |
| 81 | 1 | equemene | IF (INCY.LT.0) KY = 1 + (1-N)*INCY |
| 82 | 1 | equemene | DO 10 I = 1,N |
| 83 | 1 | equemene | DSDOT = DSDOT + DBLE(SX(KX))*DBLE(SY(KY)) |
| 84 | 1 | equemene | KX = KX + INCX |
| 85 | 1 | equemene | KY = KY + INCY |
| 86 | 1 | equemene | 10 CONTINUE |
| 87 | 1 | equemene | RETURN |
| 88 | 1 | equemene | * |
| 89 | 1 | equemene | * Code for equal, positive, non-unit increments. |
| 90 | 1 | equemene | * |
| 91 | 1 | equemene | 20 NS = N*INCX |
| 92 | 1 | equemene | DO 30 I = 1,NS,INCX |
| 93 | 1 | equemene | DSDOT = DSDOT + DBLE(SX(I))*DBLE(SY(I)) |
| 94 | 1 | equemene | 30 CONTINUE |
| 95 | 1 | equemene | RETURN |
| 96 | 1 | equemene | END |