function fcncaller(fcn, x) 
% fcncaller Calling functions with other functions as arguments [PHYS210-DEMO]
%
% See tfcncaller for a script that uses this function.
%
% fcncaller takes two input arguments:
%
%    fcn is a so-called "function handle" which can be used with a syntax 
%    identical to any other Matlab function invocation.  In this case,
%    fcn should be a function of one input argument and be capable of 
%    returning a vector of values should that input be a vector. 
%    Any of the standard mathematical functions such as sin, cos, sqrt 
%    etc. are examples.
%
%    x should be a vector of values at which the function is to be 
%    evaluated.
% 
% The function simply makes a plot of fcn(x) vs x and returns.
   plot(x, fcn(x));
end
