prtDataGenMary  Generate unimodal M-ary example data
 
   DATASET = prtDataGenMary returns a prtDataSetClass with randomly
   generated data according to the following distribution.
 
        H1: N([0 0],0.5*eye(2))
        H2: N([0.5 0.5],0.1*eye(2))
        H3: N([-2 -2],eye(2))
 
   Example:
 
   ds = prtDataGenMary;
   plot(ds)