Deco calculation oddities..

Dirk Hohndel dirk at
Fri Feb 8 03:16:26 PST 2013

"Robert C. Helling" <helling at> writes:

> On Fri, 8 Feb 2013, Linus Torvalds wrote:
> Linus,
>> IOW, I am much happier seeing that there is no long-term state that is
>> affected by the whole gradient factor, because that fundamentally
>> makes it a sensible operation to look at the same tissue loading state
>> using two different gradient factors.
> Thinking about this a bit more, I just realized that there is a little bit 
> of memory involved: It comes in with lowest_ceiling: GF_low is supposed to 
> apply at the depth of the deepest deco stop (and not at the max_depth as 
> it was in my first version of deco.c). For the linear interpolation of 
> gradient factors we need to memorize this value.
> And I would say this this depth should have no influence on the no flight 
> time. This is another reason to use for that calculation GF_high=GF_low = 
> (either 100% for plain vanilla Buehlmann or some reasonable GF_high like 
> 80% or so). Having both equal makes, as I said earlier, the gradient 
> factor independent of the ambient pressure.

But since all the waiting is done on the surface there should be NO
IMPACT. Fundamentally at the surface only GFhigh is relevant, right? And
Linus is fixing that to 75 (or something - too lazy to check) in his


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