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#### dot_product

Computes the dot product (or scalar product) of 2 vectors (points).

###### Synopsis

    template<typename Point1, typename Point2>
    select_coordinate_type< Point1, Point2 >::type dot_product(Point1 const & p1, Point2 const & p2)

###### Parameters

Type | Concept | Name | Description
--- | --- | --- | ---
Point1 const & | Any type fulfilling a Point Concept | p1 | first point
Point2 const & | Any type fulfilling a Point Concept | p2 | second point

###### Returns

the dot product

###### Header

Either

`#include <boost/geometry.hpp>`

Or

`#include <boost/geometry/arithmetic/dot_product.hpp>`

###### Examples

Calculate the dot product of two points

    #include <iostream>

    #include <boost/geometry.hpp>
    #include <boost/geometry/arithmetic/dot_product.hpp>
    #include <boost/geometry/geometries/adapted/boost_array.hpp>

    namespace bg = boost::geometry;

    BOOST_GEOMETRY_REGISTER_BOOST_ARRAY_CS(cs::cartesian)

    int main()
    {
         double dp1,dp2,dp3,dp4;
         bg::model::point<double, 3, bg::cs::cartesian> point1(1.0, 2.0, 3.0);
         bg::model::point<double, 3, bg::cs::cartesian> point2(4.0, 5.0, 6.0);

         //Example 1
         dp1 = bg::dot_product(point1, point2);

         std::cout << "Dot Product 1: "<< dp1 << std::endl;

         bg::model::point<double, 2, bg::cs::cartesian> point3(3.0, 2.0);
         bg::model::point<double, 2, bg::cs::cartesian> point4(4.0, 7.0);

         //Example 2
         dp2 = bg::dot_product(point3, point4);

         std::cout << "Dot Product 2: "<< dp2 << std::endl;

         boost::array<double, 2> a =  {1, 2};
         boost::array<double, 2> b =  {2, 3};

         //Example 3
         dp3 = bg::dot_product(a, b);

         std::cout << "Dot Product 3: "<< dp3 << std::endl;

         return 0;

    }

| Convenient namespace alias

Output:

    Dot Product 1: 32
    Dot Product 2: 26
    Dot Product 3: 8