CHOOSE is the jCommon module of jLab.

 CHOOSE  Binomial coefficient: CHOOSE(N,K) = N!K!/(N-K)!
 
    CHOOSE(N,K) returns the binomial coefficient "N choose K", written
 
          ( N )         N!    
          (   )   =  --------
          ( K )      K!(N-K)!
 
    with a little imagination for the left-hand side notation.  
 
    N and K can each either be an array or a scalar, and must of course
    be the same size if they are both arrays. 
 
    Usage: b=choose(n,k);
    __________________________________________________________________
    This is part of JLAB --- type 'help jlab' for more information
    (C) 2007--2015 J.M. Lilly --- type 'help jlab_license' for details