title: Orthogonal Projection of Point onto Line
body: <p>I'm referencing a mathematics paper, but the terminology is strange, and I'm unsure of how to code the following:</p>
  
  <p>Return if the orthogonal projection of Point P exists on S(P2, P3).</p>
  
  <p>I found <code>std::inner_product</code> but not sure if thats the correct method to use. </p>