function  retval = myfcnp(x)
% usage: y = myfcnp(x)
% description: Returns ordinate vector of derivative of values of 
% myfcn at abscissa vector x, where myfcn is selected from
% the file myfcn.m -- so keep this synchronized.

% programmer: t. shores
% last rev.: 2/8/16

%retval = 2*cos(2*x); % simple test
retval = 2*cos(2*x) + sin(5*x); % bit more complicated
%retval = 0; % square wave
%retval = sin(x) + x.*cos(x); % discontinuous at right end
%retval = 2*(pi - x).*sin(x) + x.*(2*pi-x).*cos(x); % derivative discontinuous at both ends
%retval = cos(x) + 6*sin(3*x) + 4*sin(2*x).*cos(2*x);  % analytic and periodic
