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version 1.1, 2010/08/07 13:21:02
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version 1.12, 2018/05/29 07:19:41
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*> \brief \b DSDOT |
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* |
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* =========== DOCUMENTATION =========== |
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* |
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* Online html documentation available at |
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* http://www.netlib.org/lapack/explore-html/ |
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* |
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* Definition: |
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* =========== |
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* |
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* DOUBLE PRECISION FUNCTION DSDOT(N,SX,INCX,SY,INCY) |
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* |
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* .. Scalar Arguments .. |
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* INTEGER INCX,INCY,N |
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* .. |
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* .. Array Arguments .. |
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* REAL SX(*),SY(*) |
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* .. |
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* |
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* AUTHORS |
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* ======= |
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* Lawson, C. L., (JPL), Hanson, R. J., (SNLA), |
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* Kincaid, D. R., (U. of Texas), Krogh, F. T., (JPL) |
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* |
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* |
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*> \par Purpose: |
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* ============= |
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*> |
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*> \verbatim |
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*> |
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*> Compute the inner product of two vectors with extended |
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*> precision accumulation and result. |
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*> |
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*> Returns D.P. dot product accumulated in D.P., for S.P. SX and SY |
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*> DSDOT = sum for I = 0 to N-1 of SX(LX+I*INCX) * SY(LY+I*INCY), |
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*> where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is |
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*> defined in a similar way using INCY. |
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*> \endverbatim |
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* |
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* Arguments: |
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* ========== |
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* |
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*> \param[in] N |
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*> \verbatim |
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*> N is INTEGER |
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*> number of elements in input vector(s) |
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*> \endverbatim |
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*> |
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*> \param[in] SX |
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*> \verbatim |
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*> SX is REAL array, dimension(N) |
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*> single precision vector with N elements |
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*> \endverbatim |
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*> |
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*> \param[in] INCX |
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*> \verbatim |
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*> INCX is INTEGER |
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*> storage spacing between elements of SX |
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*> \endverbatim |
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*> |
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*> \param[in] SY |
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*> \verbatim |
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*> SY is REAL array, dimension(N) |
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*> single precision vector with N elements |
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*> \endverbatim |
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*> |
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*> \param[in] INCY |
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*> \verbatim |
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*> INCY is INTEGER |
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*> storage spacing between elements of SY |
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*> \endverbatim |
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*> |
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*> \result DSDOT |
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*> \verbatim |
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*> DSDOT is DOUBLE PRECISION |
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*> DSDOT double precision dot product (zero if N.LE.0) |
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*> \endverbatim |
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* |
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* Authors: |
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* ======== |
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* |
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*> \author Univ. of Tennessee |
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*> \author Univ. of California Berkeley |
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*> \author Univ. of Colorado Denver |
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*> \author NAG Ltd. |
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* |
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*> \date December 2016 |
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* |
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*> \ingroup double_blas_level1 |
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* |
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*> \par Further Details: |
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* ===================== |
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*> |
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*> \verbatim |
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*> \endverbatim |
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* |
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*> \par References: |
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* ================ |
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*> |
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*> \verbatim |
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*> |
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*> |
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*> C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T. |
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*> Krogh, Basic linear algebra subprograms for Fortran |
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*> usage, Algorithm No. 539, Transactions on Mathematical |
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*> Software 5, 3 (September 1979), pp. 308-323. |
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*> |
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*> REVISION HISTORY (YYMMDD) |
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*> |
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*> 791001 DATE WRITTEN |
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*> 890831 Modified array declarations. (WRB) |
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*> 890831 REVISION DATE from Version 3.2 |
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*> 891214 Prologue converted to Version 4.0 format. (BAB) |
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*> 920310 Corrected definition of LX in DESCRIPTION. (WRB) |
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*> 920501 Reformatted the REFERENCES section. (WRB) |
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*> 070118 Reformat to LAPACK style (JL) |
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*> \endverbatim |
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*> |
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* ===================================================================== |
| DOUBLE PRECISION FUNCTION DSDOT(N,SX,INCX,SY,INCY) |
DOUBLE PRECISION FUNCTION DSDOT(N,SX,INCX,SY,INCY) |
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* |
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* -- Reference BLAS level1 routine (version 3.7.0) -- |
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* -- Reference BLAS is a software package provided by Univ. of Tennessee, -- |
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
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* December 2016 |
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* |
| * .. Scalar Arguments .. |
* .. Scalar Arguments .. |
| INTEGER INCX,INCY,N |
INTEGER INCX,INCY,N |
| * .. |
* .. |
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| REAL SX(*),SY(*) |
REAL SX(*),SY(*) |
| * .. |
* .. |
| * |
* |
| * AUTHORS |
* Authors: |
| * ======= |
* ======== |
| * Lawson, C. L., (JPL), Hanson, R. J., (SNLA), |
* Lawson, C. L., (JPL), Hanson, R. J., (SNLA), |
| * Kincaid, D. R., (U. of Texas), Krogh, F. T., (JPL) |
* Kincaid, D. R., (U. of Texas), Krogh, F. T., (JPL) |
| * |
* |
| * Purpose |
|
| * ======= |
|
| * Compute the inner product of two vectors with extended |
|
| * precision accumulation and result. |
|
| * |
|
| * Returns D.P. dot product accumulated in D.P., for S.P. SX and SY |
|
| * DSDOT = sum for I = 0 to N-1 of SX(LX+I*INCX) * SY(LY+I*INCY), |
|
| * where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is |
|
| * defined in a similar way using INCY. |
|
| * |
|
| * Arguments |
|
| * ========= |
|
| * |
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| * N (input) INTEGER |
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| * number of elements in input vector(s) |
|
| * |
|
| * SX (input) REAL array, dimension(N) |
|
| * single precision vector with N elements |
|
| * |
|
| * INCX (input) INTEGER |
|
| * storage spacing between elements of SX |
|
| * |
|
| * SY (input) REAL array, dimension(N) |
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| * single precision vector with N elements |
|
| * |
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| * INCY (input) INTEGER |
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| * storage spacing between elements of SY |
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| * |
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| * DSDOT (output) DOUBLE PRECISION |
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| * DSDOT double precision dot product (zero if N.LE.0) |
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| * |
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| * Further Details |
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| * =============== |
|
| * |
|
| * REFERENCES |
|
| * |
|
| * C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T. |
|
| * Krogh, Basic linear algebra subprograms for Fortran |
|
| * usage, Algorithm No. 539, Transactions on Mathematical |
|
| * Software 5, 3 (September 1979), pp. 308-323. |
|
| * |
|
| * REVISION HISTORY (YYMMDD) |
|
| * |
|
| * 791001 DATE WRITTEN |
|
| * 890831 Modified array declarations. (WRB) |
|
| * 890831 REVISION DATE from Version 3.2 |
|
| * 891214 Prologue converted to Version 4.0 format. (BAB) |
|
| * 920310 Corrected definition of LX in DESCRIPTION. (WRB) |
|
| * 920501 Reformatted the REFERENCES section. (WRB) |
|
| * 070118 Reformat to LAPACK style (JL) |
|
| * |
|
| * ===================================================================== |
* ===================================================================== |
| * |
* |
| * .. Local Scalars .. |
* .. Local Scalars .. |
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| * .. |
* .. |
| DSDOT = 0.0D0 |
DSDOT = 0.0D0 |
| IF (N.LE.0) RETURN |
IF (N.LE.0) RETURN |
| IF (INCX.EQ.INCY .AND. INCX.GT.0) GO TO 20 |
IF (INCX.EQ.INCY .AND. INCX.GT.0) THEN |
| * |
* |
| * Code for unequal or nonpositive increments. |
* Code for equal, positive, non-unit increments. |
| * |
* |
| KX = 1 |
NS = N*INCX |
| KY = 1 |
DO I = 1,NS,INCX |
| IF (INCX.LT.0) KX = 1 + (1-N)*INCX |
DSDOT = DSDOT + DBLE(SX(I))*DBLE(SY(I)) |
| IF (INCY.LT.0) KY = 1 + (1-N)*INCY |
END DO |
| DO 10 I = 1,N |
ELSE |
| DSDOT = DSDOT + DBLE(SX(KX))*DBLE(SY(KY)) |
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| KX = KX + INCX |
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| KY = KY + INCY |
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| 10 CONTINUE |
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| RETURN |
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| * |
* |
| * Code for equal, positive, non-unit increments. |
* Code for unequal or nonpositive increments. |
| * |
* |
| 20 NS = N*INCX |
KX = 1 |
| DO 30 I = 1,NS,INCX |
KY = 1 |
| DSDOT = DSDOT + DBLE(SX(I))*DBLE(SY(I)) |
IF (INCX.LT.0) KX = 1 + (1-N)*INCX |
| 30 CONTINUE |
IF (INCY.LT.0) KY = 1 + (1-N)*INCY |
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DO I = 1,N |
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DSDOT = DSDOT + DBLE(SX(KX))*DBLE(SY(KY)) |
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KX = KX + INCX |
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KY = KY + INCY |
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END DO |
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END IF |
| RETURN |
RETURN |
| END |
END |
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