function [ feq, fin ] = f_sample_con( x )
feq = x(1)^2; % degenerate representation of the constraint x(1) = 0
fin = [x(2)+x(3)-0.8;
exp(x(3))-1-x(4)];
% a linear inequality constraint but treated like a nonlinear inequality
% followed by the convex constraint x(4) >= exp(x(3))-1
end