title: nonlinear map from one range to another
body: <p>I have a maths problem I am somewhat stumped on.  I need to map a numbers from one range to another in a nonlinear fashion.  I have manually taken some sample data from what I am trying to achieve.  That looks as such.</p>
  
  <p>source - desired result</p>
  
  <p>0 - 1</p>
  
  <p>78 - 0.885</p>
  
  <p>363 - 0.625</p>
  
  <p>1429 - 0.3</p>
  
  <p>3404 - 0.155</p>
  
  <p>7524 - 0.075</p>
  
  <p>11604 - 0.05 </p>
  
  <p>The source number ranges from 0 to, ideally an infinite number, but happy if it stops somewhere in the 10s of thousands.  The resultant number is from 1 to 0.  It needs to drop off quickly then level off.  Ideally never reaching zero.</p>
  
  <p>I am aware of the standard equation to map from one range to another.</p>
  
  <pre><code>y = ((x * origRange) / newRange) + newRangeOffset
  </code></pre>
  
  <p>Unfortunately this does not give me the desired results.  Is there a elegant nonlinear equation that would give me the results I am after?</p>