title: algorithm to map values to unit scale with logarithmic spacing
body: <p>I'm looking for an algorithm to map values to a unit scale with logarithmic spacing. The scale ranges from 0 to 1.  Incoming values would be in the range of 0 to 10000.</p>
  
  <p>0 maps to 0,  1 maps to .2,  10 maps to .4,  100 maps to .6
  1000 maps to .8,  10000 maps to 1.0</p>
  
  <p>Help/pointers would be appreciated.</p>