On Wed, Aug 2, 2017 at 11:44 PM, Anton Lundin <gla...@acc.umu.se> wrote: > > On the subject of SAC rate, when we interpolate the SAC between a start > and end pressure, we currently do that on _pressure_, as pressure_time. > > Since you made our gas volume calculations more correct, Ie factor for > the non linearity of gases, we now get a pretty odd momentary SAC in the > info box.
Ahh, yes. I was wondering why the SAC rate creeps up, but you are obviously correct: it's because we calculate the real SAC rate using the real volume, but the momentary one as if it's an ideal gas. > If you open dives/sac-test.xml , you will see that the SAC value in the > info box rises during the dive, as the pressure drop in the cylinder. I > understand why, but this would be really confusing for a end user. It was confusing to me too. I for some reason thought we always used the proper gas volume, but you are obviously correct that we do not. I'll fix it. I worry that I will have to make sure to use floating point throughout to avoid rounding errors when turning milli-bars pressure differences into milli-liter volume differences, but I'll just have to see. At worst, I'll just have to do a "gas_volume_fp()" the complex case, and move the "rint()" part outside. Linus _______________________________________________ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface