Direct Indexing of Function Calls (OOP Exercise)

 IndexableFunction is a class of function-handle-like objects that allow a function to be called and post-indexed in a single expression.
 
Often, in the MATLAB Central NG, I've seen people ask whether it is possible to call functions with a syntax like y=func(arg)(i) as an alternative to doing,
 
     z=func(arg);
     y=z(i);
 
Essentially, the answer is no. Standard MATLAB syntax does not allow this. However, the IndexableFunction class enables functions to be called with the very similar syntax y=func{arg}(i).
 
If you have to call and post-index a function multiple times, this might save you some keystrokes. However, the main benefit of this submission is probably as an illustration/exercise in MATLAB OOP. Also, it will give me a link to refer to whenever the discussion point pops up again in the NG (as it persistently does).
 
In general, there is no computational superiority that this syntax does or ever could bestow. Internally, the complete vector-valued output of the function is generated and then post-indexed, which is the only generic way of enabling this syntax for an arbitrary set of functions. This is because many MATLAB functions use algorithms that inherently must return a complete vector-valued output (e.g. fft(x)).
 
 USAGE:
 
   f=IndexableFunction(h)
 
 in:
 
     h: a function handle
 
 out:
 
     f: an IndexableFunction object
 
 
 EXAMPLE:
 
          >>h=@sin; %Handle to sine function
 
          >>f=IndexableFunction(h); %Create object
 
          >>h((0:.25:1)*pi) %An ordinary kind of function call
  
          ans =
  
                   0 0.7071 1.0000 0.7071 0.0000
  
          >>f{(0:.25:1)*pi}
               %Equivalent function call using the object (note the braces)
  
          ans =
  
                   0 0.7071 1.0000 0.7071 0.0000
  
  
          >>f{(0:.25:1)*pi}(3:4)
              %The same function call, but returning the 3rd and 4th component only.
  
          ans =
  
              1.0000 0.7071

The submission also contains a file LibraryStruct.mat (and the file LibraryStruct.m that created it) with a potentially useful construct. The file contains a structure S whose field names are all the methods of class @double. Each field is an IndexableFunction handle to the corresponding method. This allows you to do things like this:
 
      >> load LibraryStruct
      >>x=rand(1,4)-.5 %some data
  
      x =
  
         -0.3424 0.4706 0.4572 -0.0146
  
      >>S.abs{x}(1)
  
      ans =
  
          0.3424
  
      >>S.sort{x}(2)
  
      ans =
  
         -0.0146

Added LibraryStruct (see revised Description section for details)

Whoops. Forgot to actually upload the update .zip