function fofx=functioninderiv(x)
%
% Objective:
%   Evaluate a function at x.
%
% input variables:
%   x - value, or vector of values, at which to evaluate f.
%
% output variables:
%   fofx - function value, or vector thereof.
%
%fofx=sin(x)+2*cos(x);
fofx=sin(x)+2*cos(x)+4*exp(-x);
fofx=sin(x)+2*cos(x)+(x-1).*(x-1).*sign(x-1);