On Thu, Oct 30, 2014 at 5:17 PM, Linus Torvalds torvalds@linux-foundation.org wrote:
On Wed, Oct 29, 2014 at 5:00 PM, Artur Wroblewski wrobell@pld-linux.org wrote:
The 15 tissue compartments half-times are documented in the Suunto manual.
Hmm. Interesting. I hadn't actually noticed that, but right you are. Not that they are exhaustively documented, but the Nitrogen half-times for the compartments are indeed there (with "halftimes are divided by a constant factor to obtain helium halftimes")
It seems, I have exaggerated the documentation part. The constant is probably around 2.65 (helium diffuses 2.65 faster than nitrogen). In [1] Wienke says "around 2.7" (pages 82-83) or "around 2.65" (i.e. page 143). Also, divide the Buhlmann nitrogen half-times by helium ones (5 / 1.88 == 2.66).
IMHO, there is much more value in such information than in Subsurface's recalculation of inert gas pressure in tissue compartment recalculation with Buhlmann.
I'm not sure that follows, though.. The ones we calculate are much better documented, and at least as well-tested as the one Suunto does, and you can actually see how changing the values and settings changes things, and how it affects the loading during the dive - while I can only download the saturation before/after the dive, with no logging of it during..
OK. I misread your e-mail thinking you get the data during the dive as well.
[...]
Anyway, you have pressure of inert gas in tissue compartments. An application using libdivecomputer could fetch the data to calculate surface intervals, no fly time and for multi-day dive planning or apply it to some other use cases we cannot predict here. A calculation does not have to use the same decompression model principles as the one implemented in a dive computer.
Inert gas pressure in tissue compartments data is quite common in many decompression models (ZH-L16, VVAL 18, VPM, RGBM) and, if I understand well, the Cochran backend could provide such data, too. We could ask HeinrichsWeikamp to have it in OSTC dive computers.
Therefore, IMHO, it would be good to model this data as, for example, a list of pressure values (in unit used by libdivecomputer for pressure) for each inert gas (but not strings).
Regards,
w