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VPMB: calculate deco_time assuming final ascent always takes the same time

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If we consider the actual time to ascend from the final stop when calculating
deco_time, then slowing the final ascent can lead to the final stop being
extended, which is completely nonsensical.  For consistency with the original
VPMB implementation, we can't ignore the final ascent time completely, but if
we assume it is always the same (take default ascent rate of 9m/min) then
slower the final ascent won't lead to a longer final stop.

Signed-off-by: Rick Walsh <rickmwalsh@gmail.com>
This commit is contained in:
Rick Walsh 2017-11-02 19:34:45 +11:00
parent 03c91a197d
commit d15779a27c
2 changed files with 7 additions and 4 deletions
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7
core/planner.c
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@ -1060,8 +1060,11 @@ bool plan(struct diveplan *diveplan, struct dive *dive, int timestep, struct dec
stopping = false;
}
}
deco_time = clock - deco_state->bottom_time;
/* When calculating deco_time, we should pretend the final ascent rate is always the same,
* otherwise odd things can happen, such as CVA causing the final ascent to start *later*
* if the ascent rate is slower, which is completely nonsensical.
* Assume final ascent takes 20s, which is the time taken to ascend at 9m/min from 3m */
deco_time = clock - deco_state->bottom_time - stoplevels[2] / last_ascend_rate + 20;
} while (!is_final_plan);
decostoptable[decostopcounter].depth = 0;

4
core/profile.c
View file

@ -1084,9 +1084,9 @@ void calculate_deco_information(struct dive *dive, struct divecomputer *dc, stru
if (final_tts > 0)
deco_time = pi->maxtime + final_tts - time_deep_ceiling;
else if (time_clear_ceiling > 0)
/* Consistent with planner, deco_time ends after ascending (20-40s @9m/min from 3-6m)
/* Consistent with planner, deco_time ends after ascending (20s @9m/min from 3m)
at end of whole minute after clearing ceiling */
deco_time = ROUND_UP(time_clear_ceiling, 60) + 30 - time_deep_ceiling;
deco_time = ROUND_UP(time_clear_ceiling, 60) + 20 - time_deep_ceiling;
vpmb_next_gradient(deco_time, surface_pressure / 1000.0);
final_tts = 0;
last_ndl_tts_calc_time = 0;