 be the name of a variable bound to a 
  MATRIX in the base (global) environment.  This matrix is displayed as an 
  image, with the title set to the string.
  
  RANGE (optional) is a 2-vector specifying the values that map to
  black and white, respectively.  Passing a value of 'auto' (default)
  sets RANGE=[min,max] (as in MatLab's imagesc).  'auto2' sets
  RANGE=[mean-2*stdev, mean+2*stdev].  'auto3' sets
  RANGE=[p1-(p2-p1)/8, p2+(p2-p1)/8], where p1 is the 10th percentile
  value of the sorted MATRIX 