Hi Robert, hi Rick, hi All,
Am 15.02.2017 um 02:23 schrieb Rick Walsh: > On 15 February 2017 at 06:50, Stefan Fuchs <[email protected] > <mailto:[email protected]>> wrote: > > Hi All, > > Joachim (R.) and I finished our first basic version of the minimum > gas calculation for the planner. > We are now looking for testing and feedback :-) > > Great work on tackling this. It's really good to see new ideas and > new developers contributing to the code. I will test when I get a > chance, which unfortunately won't be for a few days. In the meantime, > I have a few comments/suggestions. Thanks! Despite the fact that I still have to learn a lot this is really fun :-) > More details below... > > Link to initial idea and discussion: > https://github.com/Subsurface-divelog/subsurface/issues/188 > <https://github.com/Subsurface-divelog/subsurface/issues/188> > > Link to feature branch on Github: > https://github.com/sfuchs79/subsurface/tree/feature_minimum_gas > <https://github.com/sfuchs79/subsurface/tree/feature_minimum_gas> > > > My feedback to comments from Robert and Joachim (B.): > [...] > - Support rec dives: Yes, clearly, calculation is active for all > OC dives. I put some limitations for min depth (>18m) and min tank > size (12l). Calculating minimum gas for smaller cylinders is from > my point of view almost useless. > > I don't see the reason for limiting tank size and depth. 10.5l steel > cylinders are pretty common where I dive, and AL80 (11.1l) cylinders > are the most common in warm water. Also there are smaller 300bar > cylinders popular in some areas. Minimum gas is also relevant for > bailout cylinders, and some people use AL40 (5.6l) for them (although > we don't do any automatic bailout calculations). Surely having > sufficient gas is just as important a consideration for small cylinders. Ok, agreed. Let's remove this limit completely. I at the beginning was unhappy that my implementation was also showing such results like "your minimum gas is 537bar" if you select a small cylinder ;-) But I meanwhile avoid this with the simple check of minimum gas result against the starting pressure of the cylinder and print a warning instead of any result then. One may say this is also still not perfect but for me at the moment it's good enough. > I agree minimum gas is usually less of a concern for shallow dives, > but spend an hour or more at 18m on air without a deco cylinder and > you will require a significant amount of gas to allow two divers to > surface safely. Do we gain anything by excluding this possibility? Hmm.. maybe 18m is really not a good decision. It's really arbitrary as Robert is saying. What I would like to avoid is that we are printing a minimum gas result in case we replan a dive and the calculated planner points including all deco stops are still in the user entry table (before one deletes them). May I propose a compromise here: Lets use last/2nd last deco stop depth (at ~6m) as limit. This is much less arbitrary than choosing 18m. > > Robert mentioned this his comments, so sorry to repeat, but where > possible try to use the special unit types defined in core/dive.h: > duration_t (unit seconds), depth_t (unit mm), pressure_t (unit mbar), > volume_t (unit ml). It's a little bit of extra work, but it makes the > code clearer to read and debug. Obviously the UI should present the > values in friendly units. For this and all the other comments from Robert I hope I understood everything and there is nothing to discuss. Updated version will come soon. BTW: The types are in units.h ;-) A very important hint came from Robert about why we add the two new variables to struct diveplan. This was clearly a mistake is not needed. I will remove it. Best regards Stefan -- Stefan Fuchs E-Mail: [email protected] <mailto:[email protected]>
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