Numerics iteration boundary issue in ._d() about pyromat

[chmarti1]

It's starting to look like a specialized bracketing function could be a good idea instead of requiring each code segment that calls _hybrid1() to define its own bracket. It's clear that there are enough nuances to the bracketing problem that it is not efficient to solve them one-by-one. This is now my first priority for v2.2.2.

[chmarti1]

Addendum... This is actually another instance of Issue #46. The default upper density for methane is 1600 kg/m3. However, densities that high are so far out of methane's practical range that pressure cannot be reasonably extrapolated that far. p() passes an inflection and becomes negative - hence the bracket problem.

This problem vanishes if

>>> ch4 = pm.get('mp.CH4')
>>> ch4.data['dlim'] = [0, 1000]
>>> ch4.d(p=.11707696, T=624.375)
array([0.03617947])
>>> ch4.d(p=9999, T=624.375)
array([502.41168232])

The bracketing function idea is still not a bad one, but establishing better density boundaries is a much easier fix.

[chmarti1]

This is now resolved with new density limits in version 2.2.2.