refactored liouville test examples

Mohitbalwani26 · Mohitbalwani26 · commit b08999896fd1 · 2020-04-29T16:54:48.000+05:30
diff --git a/sympy/solvers/ode/tests/test_ode.py b/sympy/solvers/ode/tests/test_ode.py
@@ -2556,52 +2556,6 @@ def test_nth_linear_constant_coeff_variation_of_parameters_simplify_False():
     assert checkodesol(eq, sol_simp, order=5, solve_for_func=False) == (True, 0)
 
 
-def test_Liouville_ODE():
-    hint = 'Liouville'
-    # The first part here used to be test_ODE_1() from test_solvers.py
-    eq1 = diff(f(x), x)/x + diff(f(x), x, x)/2 - diff(f(x), x)**2/2
-    eq1a = diff(x*exp(-f(x)), x, x)
-    # compare to test_unexpanded_Liouville_ODE() below
-    eq2 = (eq1*exp(-f(x))/exp(f(x))).expand()
-    eq3 = diff(f(x), x, x) + 1/f(x)*(diff(f(x), x))**2 + 1/x*diff(f(x), x)
-    eq4 = x*diff(f(x), x, x) + x/f(x)*diff(f(x), x)**2 + x*diff(f(x), x)
-    eq5 = Eq((x*exp(f(x))).diff(x, x), 0)
-    sol1 = Eq(f(x), log(x/(C1 + C2*x)))
-    sol1a = Eq(C1 + C2/x - exp(-f(x)), 0)
-    sol2 = sol1
-    sol3 = set(
-        [Eq(f(x), -sqrt(C1 + C2*log(x))),
-        Eq(f(x), sqrt(C1 + C2*log(x)))])
-    sol4 = set([Eq(f(x), sqrt(C1 + C2*exp(x))*exp(-x/2)),
-                Eq(f(x), -sqrt(C1 + C2*exp(x))*exp(-x/2))])
-    sol5 = Eq(f(x), log(C1 + C2/x))
-    sol1s = constant_renumber(sol1)
-    sol2s = constant_renumber(sol2)
-    sol3s = constant_renumber(sol3)
-    sol4s = constant_renumber(sol4)
-    sol5s = constant_renumber(sol5)
-    assert dsolve(eq1, hint=hint) in (sol1, sol1s)
-    assert dsolve(eq1a, hint=hint) in (sol1, sol1s)
-    assert dsolve(eq2, hint=hint) in (sol2, sol2s)
-    assert set(dsolve(eq3, hint=hint)) in (sol3, sol3s)
-    assert set(dsolve(eq4, hint=hint)) in (sol4, sol4s)
-    assert dsolve(eq5, hint=hint) in (sol5, sol5s)
-    assert checkodesol(eq1, sol1, order=2, solve_for_func=False)[0]
-    assert checkodesol(eq1a, sol1a, order=2, solve_for_func=False)[0]
-    assert checkodesol(eq2, sol2, order=2, solve_for_func=False)[0]
-    assert checkodesol(eq3, sol3, order=2, solve_for_func=False) == {(True, 0)}
-    assert checkodesol(eq4, sol4, order=2, solve_for_func=False) == {(True, 0)}
-    assert checkodesol(eq5, sol5, order=2, solve_for_func=False)[0]
-    not_Liouville1 = classify_ode(diff(f(x), x)/x + f(x)*diff(f(x), x, x)/2 -
-        diff(f(x), x)**2/2, f(x))
-    not_Liouville2 = classify_ode(diff(f(x), x)/x + diff(f(x), x, x)/2 -
-        x*diff(f(x), x)**2/2, f(x))
-    assert hint not in not_Liouville1
-    assert hint not in not_Liouville2
-    assert hint + '_Integral' not in not_Liouville1
-    assert hint + '_Integral' not in not_Liouville2
-
-
 def test_unexpanded_Liouville_ODE():
     # This is the same as eq1 from test_Liouville_ODE() above.
     eq1 = diff(f(x), x)/x + diff(f(x), x, x)/2 - diff(f(x), x)**2/2
diff --git a/sympy/solvers/ode/tests/test_single.py b/sympy/solvers/ode/tests/test_single.py
@@ -330,6 +330,21 @@ def test_1st_linear():
 def test_almost_linear():
    _ode_solver_test(_get_examples_ode_sol_almost_linear())
 
+
+def test_Liouville_ODE():
+    hint = 'Liouville'
+    not_Liouville1 = classify_ode(diff(f(x), x)/x + f(x)*diff(f(x), x, x)/2 -
+        diff(f(x), x)**2/2, f(x))
+    not_Liouville2 = classify_ode(diff(f(x), x)/x + diff(f(x), x, x)/2 -
+        x*diff(f(x), x)**2/2, f(x))
+    assert hint not in not_Liouville1
+    assert hint not in not_Liouville2
+    assert hint + '_Integral' not in not_Liouville1
+    assert hint + '_Integral' not in not_Liouville2
+
+    _ode_solver_test(_get_examples_ode_sol_liouville())
+
+
 def test_nth_order_linear_euler_eq_homogeneous():
     x, t, a, b, c = symbols('x t a b c')
     y = Function('y')
@@ -690,6 +705,45 @@ def _get_examples_ode_sol_almost_linear():
     }
 
 
+def _get_examples_ode_sol_liouville():
+    return {
+            'hint': "Liouville",
+            'func': f(x),
+            'examples':{
+    'liouville_01': {
+        'eq': diff(f(x), x)/x + diff(f(x), x, x)/2 - diff(f(x), x)**2/2,
+        'sol': [Eq(f(x), log(x/(C1 + C2*x)))],
+
+    },
+
+    'liouville_02': {
+        'eq': diff(x*exp(-f(x)), x, x),
+        'sol': [Eq(f(x), log(x/(C1 + C2*x)))]
+    },
+
+    'liouville_03': {
+        'eq':  ((diff(f(x), x)/x + diff(f(x), x, x)/2 - diff(f(x), x)**2/2)*exp(-f(x))/exp(f(x))).expand(),
+        'sol': [Eq(f(x), log(x/(C1 + C2*x)))]
+    },
+
+    'liouville_04': {
+        'eq': diff(f(x), x, x) + 1/f(x)*(diff(f(x), x))**2 + 1/x*diff(f(x), x),
+        'sol': [Eq(f(x), -sqrt(C1 + C2*log(x))), Eq(f(x), sqrt(C1 + C2*log(x)))],
+    },
+
+    'liouville_05': {
+        'eq': x*diff(f(x), x, x) + x/f(x)*diff(f(x), x)**2 + x*diff(f(x), x),
+        'sol': [Eq(f(x), -sqrt(C1 + C2*exp(-x))), Eq(f(x), sqrt(C1 + C2*exp(-x)))],
+    },
+
+    'liouville_06': {
+        'eq': Eq((x*exp(f(x))).diff(x, x), 0),
+        'sol': [Eq(f(x), log(C1 + C2/x))],
+    },
+    }
+    }
+
+
 def _get_examples_ode_sol_nth_algebraic():
     M, m, r, t = symbols('M m r t')
     phi = Function('phi')
