Check if ode_in_x is truly cleared

Author: hirish99

sumpy/recurrence.py

@@ -187,9 +187,8 @@ def ode_in_x_to_coeff_array(poly: sp.Poly, ode_order: int,
     def kronecker(i, n=ode_order+1):
         return tuple(1 if i == j else 0 for j in range(n))
 
-    return [
-        sp.Poly(poly.coeff_monomial(kronecker(deriv_ind)), var[0]).all_coeffs()[::-1]
-        for deriv_ind in range(ode_order+1)
+    return [sp.Poly(poly.coeff_monomial(kronecker(deriv_ind)),
+                    var[0]).all_coeffs()[::-1] for deriv_ind in range(ode_order+1)]
 
 
 def _auto_product_rule_single_term(p: int, m: int, var: np.ndarray) -> sp.Expr:
@@ -247,9 +246,8 @@ def recurrence_from_pde(pde: LinearPDESystemOperator) -> sp.Expr:
     ode_in_r, var, ode_order = pde_to_ode_in_r(pde)
     ode_in_x = ode_in_r_to_x(ode_in_r, var, ode_order).simplify()
     ode_in_x_cleared = (ode_in_x * var[0]**(ode_order+1)).simplify()
-
-    assert is_actually_cleared()
-
+    #ode_in_x_cleared shouldn't have rational function coefficients in the coord.
+    assert sp.together(ode_in_x_cleared) == ode_in_x_cleared
     f_x_derivs = _make_sympy_vec("f_x", ode_order+1)
     poly = sp.Poly(ode_in_x_cleared, *f_x_derivs)
     coeffs = ode_in_x_to_coeff_array(poly, ode_order, var)