samer@4: function X=fold(fn,args)
samer@4: % fold - Fold combinator from functional programming
samer@4: %
samer@4: % This function applies an associative operator to a list of arguments,
samer@4: % as if the list was written out with the operator between consecutive
samer@4: % elements, eg fold(@plus,{1,2,3,4}) = 1+2+3+4.
samer@4: %
samer@4: % fold :: 
samer@4: %    (X,X->X)	~'associative binary operator',
samer@4: %    {[N]->X} ~'list (cell array) of arguments (at least 2 elements)'
samer@4: % -> X.
samer@4: 
samer@4: if isempty(args), X=[]; else X=foldl(fn,args{1},args(2:end)); end