routines.py 文件源码

def diff_approx(self, fields, pars, eps=1E-8):
        nvar, N = len(fields.dependent_variables), fields.size
        fpars = {key: pars[key] for key in self.pars}
        fpars['dx'] = (fields['x'][-1] - fields['x'][0]) / fields['x'].size
        J = np.zeros((N * nvar, N * nvar))
        indices = np.indices(fields.uarray.shape)
        for i, (var_index, node_index) in enumerate(zip(*map(np.ravel,
                                                             indices))):
            fields_plus = fields.copy()
            fields_plus.uarray[var_index, node_index] += eps
            fields_moins = fields.copy()
            fields_moins.uarray[var_index, node_index] -= eps
            Fplus = self(fields_plus, pars)
            Fmoins = self(fields_moins, pars)
            J[i] = (Fplus - Fmoins) / (2 * eps)

        return J.T