256 lines
6.7 KiB
Fortran
256 lines
6.7 KiB
Fortran
*> \brief \b SDSDOT
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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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* REAL FUNCTION SDSDOT(N,SB,SX,INCX,SY,INCY)
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*
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* .. Scalar Arguments ..
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* REAL SB
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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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* PURPOSE
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* =======
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*
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* Compute the inner product of two vectors with extended
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* precision accumulation.
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*
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* Returns S.P. result with dot product accumulated in D.P.
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* SDSDOT = SB + 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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*
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* AUTHOR
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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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* ARGUMENTS
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* =========
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*
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* N (input) INTEGER
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* number of elements in input vector(s)
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*
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* SB (input) REAL
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* single precision scalar to be added to inner product
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*
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* SX (input) REAL array, dimension (N)
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* single precision vector with N elements
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*
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* INCX (input) INTEGER
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* storage spacing between elements of SX
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*
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* SY (input) REAL array, dimension (N)
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* single precision vector with N elements
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*
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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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* SDSDOT (output) REAL
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* single precision dot product (SB if N .LE. 0)
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*
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* Further Details
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* ===============
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*
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* REFERENCES
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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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* 890531 Changed all specific intrinsics to generic. (WRB)
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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 coding style
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*
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* =====================================================================
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*
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* .. Local Scalars ..
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* DOUBLE PRECISION DSDOT
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* INTEGER I,KX,KY,NS
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* ..
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* .. Intrinsic Functions ..
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* INTRINSIC DBLE
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* ..
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* DSDOT = SB
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* IF (N.LE.0) THEN
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* SDSDOT = DSDOT
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* RETURN
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* END IF
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* IF (INCX.EQ.INCY .AND. INCX.GT.0) THEN
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*
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* Code for equal and positive increments.
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*
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* NS = N*INCX
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* DO I = 1,NS,INCX
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* DSDOT = DSDOT + DBLE(SX(I))*DBLE(SY(I))
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* END DO
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* ELSE
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*
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* Code for unequal or nonpositive increments.
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*
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* KX = 1
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* KY = 1
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* IF (INCX.LT.0) KX = 1 + (1-N)*INCX
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* 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
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* SDSDOT = DSDOT
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* RETURN
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* END
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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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*> \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 November 2011
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*
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*> \ingroup single_blas_level1
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*
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* =====================================================================
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REAL FUNCTION SDSDOT(N,SB,SX,INCX,SY,INCY)
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*
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* -- Reference BLAS level1 routine (version 3.4.0) --
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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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* November 2011
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*
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* .. Scalar Arguments ..
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REAL SB
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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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* PURPOSE
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* =======
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*
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* Compute the inner product of two vectors with extended
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* precision accumulation.
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*
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* Returns S.P. result with dot product accumulated in D.P.
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* SDSDOT = SB + 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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*
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* AUTHOR
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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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* ARGUMENTS
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* =========
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*
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* N (input) INTEGER
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* number of elements in input vector(s)
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*
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* SB (input) REAL
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* single precision scalar to be added to inner product
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*
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* SX (input) REAL array, dimension (N)
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* single precision vector with N elements
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*
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* INCX (input) INTEGER
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* storage spacing between elements of SX
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*
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* SY (input) REAL array, dimension (N)
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* single precision vector with N elements
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*
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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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* SDSDOT (output) REAL
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* single precision dot product (SB if N .LE. 0)
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*
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* Further Details
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* ===============
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*
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* REFERENCES
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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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* 890531 Changed all specific intrinsics to generic. (WRB)
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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 coding style
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*
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* =====================================================================
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*
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* .. Local Scalars ..
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DOUBLE PRECISION DSDOT
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INTEGER I,KX,KY,NS
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC DBLE
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* ..
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DSDOT = SB
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IF (N.LE.0) THEN
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SDSDOT = DSDOT
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RETURN
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END IF
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IF (INCX.EQ.INCY .AND. INCX.GT.0) THEN
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*
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* Code for equal and positive increments.
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*
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NS = N*INCX
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DO I = 1,NS,INCX
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DSDOT = DSDOT + DBLE(SX(I))*DBLE(SY(I))
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END DO
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ELSE
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*
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* Code for unequal or nonpositive increments.
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*
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KX = 1
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KY = 1
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IF (INCX.LT.0) KX = 1 + (1-N)*INCX
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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
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SDSDOT = DSDOT
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RETURN
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END
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