Level Curve Plotter

\textrm{Use this app to view, in 2D, graphs for the family of equations} \newline G(x,y) = C \; \textrm{ at user-specified levels } C.\; \textrm{ If you would like to overlay the} \newline \textrm{direction field for a first order ordinary differential equation } \; y' = f(x,y), \textrm{ } \newline \textrm{you have the option of defining this } \; f(x,y) \; \textrm{ and checking the addDirField box.}