DSDOT(3)

SYNOPSIS
DOUBLE PRECISION FUNCTION DSDOT (N, SX, INCX, SY, INCY)

NAME
dsdot - Compute the inner product of two vectors with extended precision accumulation and result.

LIBRARY
SLATEC (BLAS)

CATEGORY
D1A4

TYPE
DOUBLE PRECISION (DSDOT-D, DCDOT-C)

KEYWORDS
BLAS, COMPLEX VECTORS, DOT PRODUCT, INNER PRODUCT, LINEAR ALGEBRA, VECTOR

AUTHOR
Lawson, C. L., (JPL) Hanson, R. J., (SNLA) Kincaid, D. R., (U. of Texas) Krogh, F. T., (JPL)

DESCRIPTION
B L A S Subprogram Description of Parameters --Input-- N number of elements in input vector(s) SX single precision vector with N elements INCX storage spacing between elements of SX SY single precision vector with N elements INCY storage spacing between elements of SY --Output-- DSDOT double precision dot product (zero if N.LE.0) 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.

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.

ROUTINES CALLED
(NONE)

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)