*> \brief \b SDSDOT * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * REAL FUNCTION SDSDOT(N,SB,SX,INCX,SY,INCY) * * .. Scalar Arguments .. * REAL SB * INTEGER INCX,INCY,N * .. * .. Array Arguments .. * REAL SX(*),SY(*) * .. * *> \par Purpose: * ============= *> *> \verbatim *> *> Compute the inner product of two vectors with extended *> precision accumulation. *> *> Returns S.P. result with dot product accumulated in D.P. *> SDSDOT = SB + 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. *> \endverbatim * * Arguments: * ========== * *> \param[in] N *> \verbatim *> N is INTEGER *> number of elements in input vector(s) *> \endverbatim *> *> \param[in] SB *> \verbatim *> SB is REAL *> single precision scalar to be added to inner product *> \endverbatim *> *> \param[in] SX *> \verbatim *> SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) *> single precision vector with N elements *> \endverbatim *> *> \param[in] INCX *> \verbatim *> INCX is INTEGER *> storage spacing between elements of SX *> \endverbatim *> *> \param[in] SY *> \verbatim *> SY is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) *> single precision vector with N elements *> \endverbatim *> *> \param[in] INCY *> \verbatim *> INCY is INTEGER *> storage spacing between elements of SY *> \endverbatim * * Authors: * ======== * *> \author Lawson, C. L., (JPL), Hanson, R. J., (SNLA), *> \author Kincaid, D. R., (U. of Texas), Krogh, F. T., (JPL) * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \date November 2017 * *> \ingroup single_blas_level1 * *> \par Further Details: * ===================== *> *> \verbatim *> *> 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 *> 890531 Changed all specific intrinsics to generic. (WRB) *> 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 coding style *> \endverbatim *> * ===================================================================== REAL FUNCTION SDSDOT(N,SB,SX,INCX,SY,INCY) * * -- Reference BLAS level1 routine (version 3.8.0) -- * -- Reference BLAS is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * November 2017 * * .. Scalar Arguments .. REAL SB INTEGER INCX,INCY,N * .. * .. Array Arguments .. REAL SX(*),SY(*) * .. Local Scalars .. DOUBLE PRECISION DSDOT INTEGER I,KX,KY,NS * .. * .. Intrinsic Functions .. INTRINSIC DBLE * .. DSDOT = SB IF (N.LE.0) THEN SDSDOT = DSDOT RETURN END IF IF (INCX.EQ.INCY .AND. INCX.GT.0) THEN * * Code for equal and positive increments. * NS = N*INCX DO I = 1,NS,INCX DSDOT = DSDOT + DBLE(SX(I))*DBLE(SY(I)) END DO ELSE * * Code for unequal or nonpositive increments. * KX = 1 KY = 1 IF (INCX.LT.0) KX = 1 + (1-N)*INCX IF (INCY.LT.0) KY = 1 + (1-N)*INCY DO I = 1,N DSDOT = DSDOT + DBLE(SX(KX))*DBLE(SY(KY)) KX = KX + INCX KY = KY + INCY END DO END IF SDSDOT = DSDOT RETURN END