Poseidon CCR dives: Nitrogen loading - the solution

[Willem Ferguson]

Robert,
I have finally seen the light. I apologise for a swathe of confusing
messages today. I have diagnosed the problem and it should be pretty
easy to fix. What I should have seen in two minutes has taken me several
hours of work.

Your patch causes all references to cylinder 0 to be returned as a
reference to cylinder 1. So, in principle, cylinder 0 cannot be
referenced. The logic that does the cylinder pressure calculations are
critically dependent on being able to reference cylinder 0 because of
the required interpolation structures that must have an index of 0. So,
what happens at the moment is that the oxygen cylinder pressures are
overwritten over the diluent pressures because references to the oxygen
pressures (index 0) are returned as index 1, thus overwriting the data
for cylinder 1. Therefore the end pressures are the same for both oxygen
and diluent cylinders. The diluent series is slightly longer, therefore
the start of the diluent series is not overwritten.

Unless you think that the problem should be solved elsewhere, I will
invert the logic about cylinder numbers within gaspressures.c so that,
when the oxygen pressures is addressed it will create a 'pseudo-cylinder
0' and work with that.

Would this be a suitable solution or would you like to do something else?
Kind regards,
willem