def solve_nonlinear(self, params, unknowns, resids):

        x = hash(params['x'])
        y = params['y']

        unknowns['f_xy'] = (x-3.0)**2 + x*y + (y+4.0)**2 - 3.0
f(x,y) = (x-3)^2 + xy + (y+4)^2 - 3
dataset/ETHPy150Open OpenMDAO/OpenMDAO/openmdao/core/test/test_pbo_desvar.py/PassByObjParaboloid.solve_nonlinear