dynamic sampler bug, incorrect logl interval

While running dynesty dynamic sampler thousands of times I’m occasionally hitting the error “cannot find live points in the required logl interval”. To debug it I put additional print there. See below:

  File "ZZZ/pyenv38/lib/python3.6/site-packages/dynesty
/dynamicsampler.py", line 1669, in run_nested
    stop_val=stop_val)
  File "ZZZ/pyenv38/lib/python3.6/site-packages/dynesty
/dynamicsampler.py", line 1775, in add_batch
    save_bounds=save_bounds):
File "ZZZ/pyenv38/lib/python3.6/site-packages/dynesty/dynamicsampler.py", line 1118, in sample_batch
    raise RuntimeError('Could not find live points in the required logl interval %f %f %f %f %f %d %d %d'%(logl_min, live_logl.min(), live_logl.max(), base_logl.min(), base_logl.max(), uidx, r, i))
RuntimeError: Could not find live points in the required logl interval 2596792.346555 2596788.423530 2596790.531368 -50000000000000000000.000000 2596790.531368 435 -501 1

The important point is logl_min is > base_logl.max(). This tells me that the sample_batch here https://github.com/joshspeagle/dynesty/blob/1a3cce6f490f275919208e3bdd154139ab20b117/py/dynesty/dynamicsampler.py#L1780 is called with the logl low boundary that is above the logl of the base run. I can’t immediately figure out why this happens. (and since the error occurs sporadically on a cluster can’t really debug it). So I’ll put it here for the moment. I wonder if the weight function is incorrect somehow since it provides the bounds…

[segasai]

On that topic, I think it would be good to refactor the dynamicsampler with something like this https://github.com/segasai/dynesty/commit/316a2314ccdc957504f74d2f2452bea265cad18c because currently the code is full of

new_u.append(u)
saved_u.append(u)

and it’s hard to verify correctness with so much duplication.

Plus I wasn’t 100 % sure all the relevant arrays were properly kept in sync.

[joshspeagle]

This should now be resolved via #248, so closing this for now.