EFX
Contributor
Im still trying to comprehend the different approaches to the M gradient calculations. I have read it, not just here but elsewhere, but I don't fully understand it. It seems to stem from a difference in the way Buhlmann and was it Workman or someone else based their calculations. That is what I vaguely recall.
Would it be fair to say that one method is applicable to calculating for sea level pressure diving only. Whereas the other one can be used for calculations for sea level diving and will also produce results for diving at altitude? Or am I miss interpreting it.
Workman referenced his tissue pressures to sea level pressure which he arbitrarily set as 0 gauge pressure. Buhlmann used 0 absolute pressure. In reference to my post above regarding the two different m-value calculations, they can be done in gauge or absolute pressures as long as the surface pressure is not above sea level.
Both Baker in his program and the values in my spreadsheet work with Buhlmann a and b coefficients which use absolute pressures. Therefore, the GF or MV (Baker's so-called max m-value in his sample program output) in my ss will be calculated using absolute pressures. I have re-calculated current GF on the ss according to the method outlined in my previous posts in this thread and have verified that this is the correct approach for displaying current GF. I will post a major revision soon.
The math can be daunting. If anyone is having trouble with the math look at figure 3 in Baker's paper "Understanding M-values". The graph says it all. Baker's 91% is the % M-value on the graph. The GF calculation is % M-value gradient. I hope this helps.