The website for the VPM algorithm is here http://www.decompression.org. There are a few resources there along with some open source implementations that could be looked at as a basis of the code.
My belief is that if you wanted to compare a variety of different algorithms and all of their different variants then use a dedicated dive-planner software package (I myself use MultiDeco and Pastodeco). If you want a diving logbook with a built-in, tried and tested dive planner using pretty much the widest used algorithm then use Subsurface. When i first started planning dives there was lots of talk about VPM and it seemed very popular but since then i've noticed a steady shift to Bühlmann + Gradient Factors. The Bühlmann model (Or one very like it) is used in the vast majority of dive computers on the market. Even the Suunto RGBM algorithm which suggests is a bubble model still works more like a traditional Haldanean model. There are very few computers that use the VPM algorithm to work out 'live' deco. Regards Jason On Thu, Aug 28, 2014 at 3:47 PM, Guillaume Gardet <guillaume.gar...@free.fr> wrote: > > Le 28/08/2014 16:38, Dirk Hohndel a écrit : > >> On Thu, Aug 28, 2014 at 04:30:31PM +0200, Guillaume Gardet wrote: >> >>> For Bühlmann there are multiple models : >>> * number of tissue compartments (8, 12 or 16) >>> * A/B/C variants (at least for ZHL-16): A is theoretical only, B is for >>> tables generation and C is for dive computer (more conservative). >>> >>> So, we could implement those variants. >>> >> The biggest challenge here is "who would implement this". >> We have learned that the discrete implementation of these models is rather >> tricky (as a divelog we only get the samples at the sample rate the dive >> computer returns to us). And because of that, even if we know exactly >> which model a dive computer is designed to implement, we still usually >> don't match the deco data the dive computer shows, as it has access to the >> continuous depth information. Additionally many divecomputers have rather >> under-powered CPUs (to say the least) and they are taking serious >> shortcuts when calculating the compartment values - which also leads to >> different results. >> >> Long story short: it's not clear to me if there is value in implementing >> other variations of the Buhlmann algorithm - it's unlikely we'll ever >> perfectly "match" any dive computer you are diving. >> > > Sure we will never perfectly match logged dives, but my use case would be > more in planning mode. > > >> I'd be more interested in a VPM implementation (that is reasonably well >> documented). We had a GSOC proposal to do just that and decided not to >> accept it but it's still something that we are open to if there's a >> developer with the necessary math / physics background willing to tackle >> the problem. >> > > Do you have pointers for implementing VPM? Willem wrote it was totally > proprietary. > > > Guillaume > > _______________________________________________ > subsurface mailing list > subsurface@hohndel.org > http://lists.hohndel.org/cgi-bin/mailman/listinfo/subsurface >
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