def test_py_stage_is_called_on_gpu(self):
# Given.
stepper = S12Step()
integrator = LeapFrogIntegrator(fluid=stepper)
equations = [SHM(dest="fluid", sources=None)]
self._setup_integrator(equations=equations, integrator=integrator)
dt = 1.0
tf = dt
# When
def callback(t):
pass
self._integrate(integrator, dt, tf, callback)
self.pa.gpu.pull('x', 'u')
# Then
self.assertTrue(hasattr(stepper, 'called_with1'))
self.assertEqual(stepper.called_with1, (0.0, dt))
self.assertTrue(hasattr(stepper, 'called_with2'))
self.assertEqual(stepper.called_with2, (0.5 * dt, dt))
# These are not physically significant as the main purpose is to see
# if the py_stage* methods are called.
np.testing.assert_array_almost_equal(self.pa.x, [2.0])
np.testing.assert_array_almost_equal(self.pa.u, [1.0])
def test_integrator_calls_py_stage1(self):
# Given.
stepper = S1Step()
integrator = LeapFrogIntegrator(fluid=stepper)
equations = [SHM(dest="fluid", sources=None)]
self._setup_integrator(equations=equations, integrator=integrator)
tf = 1.0
dt = tf
# When
call_data = []
def callback(t):
call_data.append(t)
self._integrate(integrator, dt, tf, callback)
# Then
self.assertEqual(len(call_data), 1)
self.assertTrue(hasattr(stepper, 'called_with1'))
self.assertEqual(stepper.called_with1, (0.0, dt))
# These are not physically significant as the main purpose is to see
# if the py_stage* methods are called.
np.testing.assert_array_almost_equal(self.pa.x, [1.5])
np.testing.assert_array_almost_equal(self.pa.u, [0.5])
def test_detection_of_missing_arrays_for_integrator(self):
# Given.
x = np.asarray([1.0])
u = np.asarray([0.0])
h = np.ones_like(x)
pa = get_particle_array(name='fluid', x=x, u=u, h=h, m=h)
arrays = [pa]
# When
integrator = LeapFrogIntegrator(fluid=LeapFrogStep())
equations = [SHM(dest="fluid", sources=None)]
kernel = CubicSpline(dim=1)
a_eval = AccelerationEval(particle_arrays=arrays,
equations=equations,
kernel=kernel)
comp = SPHCompiler(a_eval, integrator=integrator)
# Then
self.assertRaises(RuntimeError, comp.compile)
def test_leapfrog(self):
# Given.
integrator = LeapFrogIntegrator(fluid=LeapFrogStep())
equations = [SHM(dest="fluid", sources=None)]
self._setup_integrator(equations=equations, integrator=integrator)
tf = np.pi
dt = 0.02 * tf
# When
energy = []
def callback(t):
x, u = self.pa.x[0], self.pa.u[0]
energy.append(0.5 * (x * x + u * u))
callback(0.0)
self._integrate(integrator, dt, tf, callback)
# Then
energy = np.asarray(energy)
self.assertAlmostEqual(np.max(np.abs(energy - 0.5)), 0.0, places=3)
def test_integrator_calls_only_py_when_no_stage(self):
# Given.
stepper = OnlyPyStep()
integrator = LeapFrogIntegrator(fluid=stepper)
equations = [SHM(dest="fluid", sources=None)]
self._setup_integrator(equations=equations, integrator=integrator)
tf = 1.0
dt = tf
# When
def callback(t):
pass
self._integrate(integrator, dt, tf, callback)
# Then
self.assertTrue(hasattr(stepper, 'called_with1'))
self.assertEqual(stepper.called_with1, (0.0, dt))
self.assertTrue(hasattr(stepper, 'called_with2'))
self.assertEqual(stepper.called_with2, (0.5 * dt, dt))
np.testing.assert_array_almost_equal(self.pa.x, [0.5])
np.testing.assert_array_almost_equal(self.pa.u, [1.5])
def test_leapfrog_is_second_order(self):
# Given.
integrator = LeapFrogIntegrator(fluid=LeapFrogStep())
equations = [SHM(dest="fluid", sources=None)]
self._setup_integrator(equations=equations, integrator=integrator)
# Take a dt, find the error, halve dt, and see that error is drops as
# desired.
# When
tf = np.pi
dt = 0.02 * tf
energy = []
def callback(t):
x, u = self.pa.x[0], self.pa.u[0]
energy.append(0.5 * (x * x + u * u))
callback(0.0)
self._integrate(integrator, dt, tf, callback)
energy = np.asarray(energy)
err1 = np.max(np.abs(energy - 0.5))
# When
self.pa.x[0] = 1.0
self.pa.u[0] = 0.0
energy = []
dt *= 0.5
callback(0.0)
self._integrate(integrator, dt, tf, callback)
energy = np.asarray(energy)
err2 = np.max(np.abs(energy - 0.5))
# Then
self.assertTrue(err2 < err1)
self.assertAlmostEqual(err1 / err2, 4.0, places=2)