vec_dot() — Apollo

VEC_$DOT                          Domain/OS                           VEC_$DOT


NAME
     vec_$dot - return the dot product of two single-precision vectors

SYNOPSIS (C)
     #include <apollo/base.h>
     #include <apollo/vec.h>

     float vec_$dot(
          float *vector1,
          float *vector2,
          long int &length)

SYNOPSIS (Pascal)
     %include '/sys/ins/base.ins.pas';
     %include '/sys/ins/vec.ins.pas';

     function vec_$dot(
          in vector1: univ vec_$real_vector;
          in vector2: univ vec_$real_vector;
          in length: integer32): real;

SYNOPSIS (FORTRAN)
     %include '/sys/ins/base.ins.ftn'
     %include '/sys/ins/vec.ins.ftn'

           parameter (nvec = 10)

           real vector1(nvec), vector2(nvec), result
           integer*4 length

           result = vec_$dot(vector1, vector2, length)

DESCRIPTION
     Vec_$dot returns the dot (scalar) product of two single-precision vec-
     tors, vector1 and vector2.

     In C, the resulting operation is

          return_value = 0.0;
          for (i = 0; i < length; ++i)
               return_value += vector1[i] * vector2[i];

     In Pascal, the resulting operation is

          return_value := 0.0;
          for i := 1 to length do
               begin
               return_value := return_value
                            + vector1[i] * vector2[i];
               end

     In FORTRAN, the resulting operation is

           vec_$dot = 0.0
           do 10 i = 1,length
               vec_$dot = vec_$dot + vector1(i) * vector2(i)
       10  continue

     vector1
          A vector.

     vector2
          Another vector.

     length
          The number of elements to use in calculating the dot (scalar) pro-
          duct.

NOTES
     When vec_$dot is used on matrixes in C or Pascal, vector1 and vector2 are
     row vectors; whereas in FORTRAN they are column vectors.

SEE ALSO
     vec_$ddot, vec_$dot_i, vec_$idot, vec_$idot16.
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