title: How to draw a picture with mathematical equations
body: <p>Recently I have seen some pictures that could be drawn by some mathematical equations like the <a href="http://mathworld.wolfram.com/BatmanCurve.html" rel="nofollow noreferrer">Batman Logo</a> and the <a href="http://mathworld.wolfram.com/HeartCurve.html" rel="nofollow noreferrer">Heart</a>.</p>
  <p>Is there a specific way to find the equations which draw a desired picture? (e.g. I want to draw the letter S with some mathematical equations).</p>
  <p>Thanks.</p>
  <p>p.s. I guess it is an optimization problem. First get some samples from the border of the desired picture and then finding a function which has the minimum difference from those samples.</p>