IPTION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="fragment"><pre class="comment"> Calculates the softMin of a vector.

 Let D be a vector.  Then the softMin of D is defined as:
   s = exp(-D/sigma^2) / sum( exp(-D/sigma^2) )
 The softMin is a way of taking a dissimilarity (distance) vector D and
 converting it to a similarity vector s, such that sum(s)==1. If D is an
 NxK array, is is treated as N K-dimensional vectors, and the return is
 likewise an NxK array.  This is us