function f = spfun(fun,s)
%SPFUN 	Apply a function only to the nonzero entries.
%	F = SPFUN('fun',S) evaluates fun(s) on the nonzero elements of S.
%	e.g. F = SPFUN('exp',S) has the same sparsity pattern as S
%	(except for underflow), whereas EXP(S) has 1's where S has 0's.

%	Copyright (c) 1984-93 by The MathWorks, Inc.

[i,j,x] = find(s);
f = eval( [ 'sparse(i,j,'  fun '(x))' ] );

