[PATCH 2/2] Add initial rudimentary no-fly time calculation

[Robert C. Helling]

On Fri, 8 Feb 2013, Linus Torvalds wrote:

Linus,
> On Fri, Feb 8, 2013 at 9:51 PM, Robert C. Helling <helling at lmu.de> 
wrote:

> Which would be around 13000 feet of pressure or so. Of course, they
> don't actually use Buhlmann at all (some proprietary RGBM variant),
> and they probably have different gradient factor equivalents anyway
> (since they are very conservative indeed), so the "13000 ft" thing is
> quite possibly not very close. I doubt we'll ever know..

Fair enough. And I would not be surprised if "some proprietary RGBM 
variant" ends up being marketing speak for something very similar to 
gradient factors deep inside their microcontroller.

> The "you can come up from infinitely long dives at 20ft" is due to the
> same tissue tolerance as "you can fly after an infinitely long stay at
> surface level". They are both roughly a 33% pressure drop, after all,
> well within tolerances.. No?

Pretty much, except that it seems it's more absolute differences in 
pressure that matter than percentages (actually the Buehlmann formula is a 
mixture of both).

> It does indeed vary with GF_low, but not the way you say. Lowering
> GF_low makes the no-fly time longer. I just tested with my last dive -
> with the default GFlow of 0.30, I get a no-fly of 11:05, with a GFlow
> of 0.20 I get 13:00. Which is what you'd expect from "more
> conservative value", no?

Hmm.
[...]
Hmm.

There was about an hour between typing these two Hmms in which I convinced 
myself that a) what you write is indeed the case for the current code and 
b) I still think that it should be as I said earlier.

This worries me a lot (regarding correctness of the deco calculation) and 
I will look into this.

Just not now, as I have some real work to do before the weekend comes. I 
hope to find some time tonight, if not over the weekend.

Best
Robert

-- 
.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oO
Robert C. Helling     Elite Master Course Theoretical and Mathematical Physics
                       Scientific Coordinator
 		      Ludwig Maximilians Universitaet Muenchen, Dept. Physik
print "Just another   Phone: +49 89 2180-4523  Theresienstr. 39, rm. B339
     stupid .sig\n";   http://www.atdotde.de