Subsurface minimum gas calculation - First version for review

[Robert Helling]

Stefan,

> On 20.02.2017, at 15:02, Stefan Fuchs <sfuchs at gmx.de> wrote:
> 
> Now I identified the next hurdle: Is there somewhere the curve cylinder pressure versus dive time for every specific cylinder? Or how could I create it for a specific cylinder id? I found that this is neither in struct cylinder_t, nor in dive or divecomputer. I think this somehow works with the struct sample and is created at the moment when the profile is finally created.
> What I need to do are two things:
> 1. Get the cylinder pressure for "my" "lastbottomdp" which is a struct divedatapoint *. In fact I need the pressure at time lastbottomdp.time
> 2. If this value is smaller than the minimum gas result I need to go back on the time axis and find the point in time when cylinder pressure goes below minimum gas. At this time I like to put the event/warning icon.


the problem is that for computers that don’t have gas information, the interpolation of cylinder pressures is only done at the plot stage. The information is in struct plot_data which you find in profile.h, in particular in cylinderindex and pressure[2] (to access the latter there is a macro, for usage see profile.c. Strictly speaking, that is to handle the CCR case which you want to avoid anyway but it’s better to use this as an accessor).

And as I said: I think it’s cleaner to add an event to the dive rather than plot directly to the profile. Simply use

struct event *add_event(struct divecomputer *dc, unsigned int time, int type, int flags, int value, const char *name)

from dive.c

Best
Robert

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Robert C. Helling     Elite Master Course Theoretical and Mathematical Physics
                      Scientific Coordinator
                      Ludwig Maximilians Universitaet Muenchen, Dept. Physik
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