On 22 August 2015 at 14:41, Rick Walsh <[email protected]> wrote: > The Boyle's law compensation depends on first_stop_pressure. To produce > profiles similar to other VPM-B implementations, we should calculate it as > the > ceiling before starting the ascent. > > Commit 159c9eb2c1c19dfbf650f2b0cc28e0ef1f45c964, Compare ceiling to next > stop > rather than try to ascent for VPM-B, changed (VPM-B) to consider the > current > ceiling rather than an incremental ascent between one stop level and the > next. > However, the initial ascent generally steps through several stop levels, so > first_stop_pressure was still not calculated as the ceiling prior to > commencing > the calculated ascent. > > Signed-off-by: Rick Walsh <[email protected]> >
To show what this actually does to the calculated profiles, I have made a new column on the Google docs spreadsheet Robert set up. This gets the calculated profiles noticeably closer to those calculated by other software, except for the multi-level dive (20m for 10min, then drop to 60m for 30min). I think the small difference might be related to use of Schreiner vs Haldane equations in the change in levels, but could be wrong. Note that this change alters the first_stop_pressure used for the Boyle's law compensation. The way the profile is calculated, if we get to that depth but can ascend to the next, then we do. Rick
_______________________________________________ subsurface mailing list [email protected] http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
