whfast stalls when exact_finish_time==1

[silburt]

I've been trying to get outputs of some specific timestamps using whfast, but the integrator appears to stall. I can make it stall for a couple of different examples, but attached I've constructed a specific simple example that stalls on my computer.

I think that it's coming from the fact that whfast is trying to integrate to a specific time and having trouble getting to that exact timestamp. If I set exact_finish_time = 0, the integration will complete no problem.

whfast_stall.ipynb.zip

[hannorein]

Minimal example, reproducing the issue. Note that this is not related to WHFast. Also note that the timestep is almost exactly equal to the output interval.

import rebound
import numpy as np
sim = rebound.Simulation()
sim.integrator = "leapfrog"
sim.dt = 2*np.pi* 0.64108339**(1.5) / 31.
sim.add(m=0.92)
times = np.linspace(0,60,600)
exact_finish_time = 1
for t in times:
    print(t, sim.dt)
    sim.integrate(t, exact_finish_time)

[silburt]

Yes, I agree that it's not specific to WHFast. I also noticed that it stalls when trying different integrators too. In the future, I'll try and simplify my problem even more...

[hannorein]

See also #485