fixed missing 'sign' parameter

classical/test_iln_00_1p_1d.py

 from liouville import q, p, LiouvillePowers
 
 order = 4
-ilnq = LiouvillePowers(order, function=q, hamiltonian=p**2/2, recursion='chebyshev')
-ilnp = LiouvillePowers(order, function=p, hamiltonian=p**2/2, recursion='chebyshev')
+ilnq = LiouvillePowers(order, function=q, hamiltonian=p**2/2,
+                       recursion='chebyshev', sign=1)
+ilnp = LiouvillePowers(order, function=p, hamiltonian=p**2/2,
+                       recursion='chebyshev', sign=1)
 print(ilnq, ilnp)
 print(ilnq.Lf, ilnp.Lf)

classical/test_iln_2p_1d.py

@@ -19,8 +19,8 @@ V = V.subs(r, abs(Q[0]-Q[1]))
 T = sum(p**2/2 for p in P)
 H = (V, T)
 
-ilnq = MPLP(nterms, H, Q, P, Q, recursion='chebyshev')
-ilnp = MPLP(nterms, H, Q, P, P, recursion='chebyshev')
+ilnq = MPLP(nterms, H, Q, P, Q, recursion='chebyshev', sign=1)
+ilnp = MPLP(nterms, H, Q, P, P, recursion='chebyshev', sign=1)
 print(ilnq.Lf[nterms-1])
 print(ilnp.Lf[nterms-1])
 Qval = [1, 1.1]