title: Find the intersection of two point series?
body: <p>A line is here defined as a series of 2D node points. Now, I have two such lines <code>A</code> and <code>B</code>.</p>
  
  <pre><code>A=[(0, 0), (1, 1), (2.1, 3), (4,7)]
  B=[(2, 0), (2, 6)]
  </code></pre>
  
  <p>When one draws them on the paper, one can easily see the two lines intersect at a point that is <strong>NOT</strong> a node member of either <code>A</code> or <code>B</code>.</p>
  
  <p>However, both <code>A</code> and <code>B</code> <strong>indeed cross this point</strong>. That is, the point indeed lies both on <code>A</code> and <code>B</code>, just not collide with the node points.</p>
  
  <p>I now wish to find the intersection point.</p>
  
  <p><em>(a gentle reminder once again: the intersection is on <code>A</code> and <code>B</code>, but it may not be a node)</em></p>
  
  <p>What I come up with now is to use a polynomial to fit each point series. In this way, I can solve for the intersection with the equations. However, it seems to be a quite stupid way to myself.</p>
  
  <p>Is there any smart way to do so?</p>
  
  <p>I am speaking Python, but any generic answers are also very much welcomed.</p>