SDOTI(3)     SPARSE BLAS routine of NEC Numeric Library Collection    SDOTI(3)



NAME
       SDOTI - Real indexed dot product

SYNOPSIS
       REAL FUNCTION SDOTI( NZ, X, INDX, Y )

           INTEGER        NZ, INDX

           REAL           X, Y

PURPOSE
       Sdoti  computes  the  vector  inner  product  of a real sparse vector X
       stored in compressed form ( X, INDX ) with a  real  vector  Y  in  full
       storage  form.  Only the elements of Y whose indices are listed in INDX
       are referenced.
       SDOTI computes:
                               NZ
          DOTI  <--  X * Y  =  Sum  X(i) * Y( INDX(i) )
                               i=1
       where X and Y are real vectors.

ARGUMENTS
       SDOTI   (output) REAL
               Real function value equal to the vector inner  product.  If  NZ
               .le. 0  SDOTI is set to zero.

       NZ      (input) INTEGER
               Number of elements in the compressed form.

       X       (input) REAL
               Array containing the values of the compressed form.

       INDX    (input) INTEGER
               Array containing the indices of the compressed form.

       Y       (input) REAL
               Array,  on  input,  which contains the vector Y in full storage
               form. Only the elements corresponding to the  indices  in  INDX
               will be accessed.

FURTHER DETAILS
       Sparse  BLAS  algorithm  is  from  ACM  algorithm  692 by D. Dodson, R.
       Grimes, and J. Lewis.




SPARSE BLAS routine             31 October 2017                       SDOTI(3)