4.2. Testcase #2
Now we want to determine the neutral hydrogen density from the population ratio (deduced from the observed column density ratios of UV lines in the spectrum) assuming the same physical conditions as in the previous example.
This example exploits the fact that the diagnosis curve traced in the first example is a monotonically increasing function of density.
To run this testcase the user should include the radiation field of the Galaxy in the body of function URAD in module POPRATIO:
urad = Fgal(lambda)