ITK  5.0.0
Insight Segmentation and Registration Toolkit
WikiExamples/Math/DotProduct.cxx
#include <itkVector.h>
int main(int, char*[])
{
v1[0] = 1.0;
v1[1] = 2.0;
v1[2] = 3.0;
v2[0] = 1.0;
v2[1] = 2.0;
v2[2] = 3.0;
VectorType::ComponentType dotproduct = v1*v2;
std::cout << "dot(v1,v2): " << dotproduct << std::endl;
return EXIT_SUCCESS;
}