dqdota.f

      DOUBLE PRECISION FUNCTION DQDOTA (N, DB, QC, DX, INCX, DY, INCY)
C***BEGIN PROLOGUE  DQDOTA
C***PURPOSE  Compute the inner product of two vectors with extended
C            precision accumulation and result.
C***LIBRARY   SLATEC
C***CATEGORY  D1A4
C***TYPE      DOUBLE PRECISION (DQDOTA-D)
C***KEYWORDS  DOT PRODUCT, INNER PRODUCT
C***AUTHOR  Lawson, C. L., (JPL)
C           Hanson, R. J., (SNLA)
C           Kincaid, D. R., (U. of Texas)
C           Krogh, F. T., (JPL)
C***DESCRIPTION
C
C               B L A S  Subprogram
C   Description of Parameters
C
C    --Input--
C       N  number of elements in input vector(S)
C      DB  double precision scalar to be added to inner product
C      QC  extended precision scalar to be added to inner product
C      DX  double precision vector with N elements
C    INCX  storage spacing between elements of DX
C      DY  double precision vector with N elements
C    INCY  storage spacing between elements of DY
C
C    --Output--
C  DQDOTA  double precision result
C      QC  extended precision result
C
C    D.P. dot product with extended precision accumulation (and result)
C    QC and DQDOTA are set = DB + QC + sum for I = 0 to N-1 of
C      DX(LX+I*INCX) * DY(LY+I*INCY),  where QC is an extended
C      precision result previously computed by DQDOTI or DQDOTA
C      and LX = 1 if INCX .GE. 0, else LX = (-INCX)*N, and LY is
C      defined in a similar way using INCY.  The MP package by
C      Richard P. Brent is used for the extended precision arithmetic.
C
C    Fred T. Krogh,  JPL,  1977,  June 1
C
C    The common block for the MP package is name MPCOM.  If local
C    variable I1 is zero, DQDOTA calls MPBLAS to initialize
C    the MP package and reset I1 to 1.
C
C    The argument QC(*) and the local variables QX and QY are INTEGER
C    arrays of size 30.  See the comments in the routine MPBLAS for the
C    reason for this choice.
C
C***REFERENCES  C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T.
C                 Krogh, Basic linear algebra subprograms for Fortran
C                 usage, Algorithm No. 539, Transactions on Mathematical
C                 Software 5, 3 (September 1979), pp. 308-323.
C***ROUTINES CALLED  MPADD, MPBLAS, MPCDM, MPCMD, MPMUL
C***COMMON BLOCKS    MPCOM
C***REVISION HISTORY  (YYMMDD)
C   791001  DATE WRITTEN
C   890831  Modified array declarations.  (WRB)
C   890831  REVISION DATE from Version 3.2
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C   920501  Reformatted the REFERENCES section.  (WRB)
C   930124  Increased Array sizes for SUN -r8.  (RWC)
C***END PROLOGUE  DQDOTA