minor modification to PDEcs.m
minor modification to PDEcs.m

tried with lbfgs module, however, it is a lttle buggy, and cannot use
function handle within class. Now will stick with ipopt and lbfgs/sr1
only.

Signed-off-by: Yimin <2c48d6222cea467f588d839852a50d90a4a31a59@gmail.com>
GaZ3ll3/femex,GaZ3ll3/femex,GaZ3ll3/femex,GaZ3ll3/femex