function fp = fn_prime(x)
%
% Written by:
% --
% John L. Weatherwax                2009-04-21
%
% email: wax@alum.mit.edu
%
% Please send comments and especially bug reports to the
% above email address.
%
% Problem on EPage 62; Solutions on EPage 161
%
%-----

if( x > 0 )
  fp = 3*x^2 + 1;
else
  fp = -3*x^2 + 1;
end