Allow generating a state from another state

Author: giadarol

FiniteDifferences_ShortleyWeller_SquareGrid.py

@@ -245,6 +245,8 @@ def __init__(self,chamb, Dh, sparse_solver = 'scipy_slu', tol_stem = 0.01, tol_d
 
             self.solve = self._solve_for_states
             self.sparse_solver = None
+            self.tol_stem = None
+            self.tol_der = None
 
         self.flag_inside_n_mat = np.logical_not(flag_outside_n_mat)
         self.chamb = chamb