def test_wrong_method_raises_error(ivp):
"""Methods that are not in the list raise errors."""
f = ivp.f
t0, tmax = ivp.t0, ivp.tmax
y0 = ivp.y0
wrong_methods = ["DOP853", "Radau", "LSODA", "BDF"]
for wrong_method in wrong_methods:
with pytest.raises(ValueError):
diffeq.perturbsolve_ivp(f,
t0,
tmax,
y0,
rng=rng,
method=wrong_method)
def test_wrong_perturb_raises_error(ivp):
"""Perturbation-styles that are not in the list raise errors."""
f = ivp.f
t0, tmax = ivp.t0, ivp.tmax
y0 = ivp.y0
wrong_perturbs = ["step-something", "state"]
for wrong_perturb in wrong_perturbs:
with pytest.raises(ValueError):
diffeq.perturbsolve_ivp(f,
t0,
tmax,
y0,
rng=rng,
perturb=wrong_perturb)
def test_no_step_or_tol_info_raises_error(ivp, rng):
"""Providing neither a step-size nor a tolerance raises an error."""
f = ivp.f
t0, tmax = ivp.t0, ivp.tmax
y0 = ivp.y0
with pytest.raises(ValueError):
diffeq.perturbsolve_ivp(f,
t0,
tmax,
y0,
rng,
step=None,
adaptive=True,
atol=None,
rtol=None)
def test_adaptive_solver_successful(rng, ivp, method, perturb, noise_scale,
step, tolerance, time_stops):
"""The solver terminates successfully for all sorts of parametrizations."""
sol = diffeq.perturbsolve_ivp(
f=ivp.f,
t0=ivp.t0,
tmax=ivp.tmax,
y0=ivp.y0,
rng=rng,
noise_scale=noise_scale,
perturb=perturb,
adaptive=True,
atol=tolerance,
rtol=tolerance,
method=method,
step=step,
time_stops=time_stops,
)
# Successful return value as documented
assert isinstance(sol, diffeq.ODESolution)
# Adaptive steps are not evenly distributed
step_diff = np.diff(sol.locations)
step_ratio = np.amin(step_diff) / np.amax(step_diff)
assert step_ratio < 0.5
if time_stops is not None:
for t in time_stops:
assert t in sol.locations