For this objective function value is coming in the order of e+10
You seem to think this value is large and far from the optimum, but there's no reason for the rest of us to think so. We haven't seen the value of the objective function at any other points, and so have no basis for comparison. You should plot your objective along a line connecting your initial point x0 to the final point xfinal found by fmincon, as one way to assess the reduction.
g=@(t) objective( (1-t)*x0+t*xfinal );
t=union(1, linspace(0,2,20) );
plot(t,arrayfun(g,t),'o--'); xlabel t; ylabel Objective;
