SDLAB  Create label object

     LAB=SDLAB(NAMES)
     LAB=SDLAB('class 1',count1,'class 2',count2,...)
     LAB=SDLAB('cluster ',1:10)
     LAB=SDLAB(IND,CLASSES)     % given class names and sample indices
     LAB=SDLAB(CLASSES,SIZES)   % given class names and per-class sizes

 INPUT
   NAMES     Cell array or character array
   IND       Vector with 1-based indices in CLASSES
   CLASSES   Cell array or character array with class names
   SIZES     Vector of per-class sizes

 OUTPUT
   LAB       SDLAB object

 DESCRIPTION
 SDLAB object describes a labels for a set of entries.  Each entry (data
 sample) is assigned to one category (class). Categories are described
 in a list accessible via LAB.list.