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| author |  Robert C. Helling <helling@lmu.de> | 2013-01-10 11:24:42 +0100 |
|---|---|---|
| committer |  Dirk Hohndel <dirk@hohndel.org> | 2013-01-10 09:14:55 -0800 |
| commit | 4c13f1f6b4ad7deb2071fb4848ddf43be0af4db7 (patch) | |
| tree | 3321ab45971daa2a84c6d66045764c53adb4477e | |
| parent | 1aa3c0d5147df7ef8846c955dffe7227257c5ca1 (diff) | |
| download | subsurface-4c13f1f6b4ad7deb2071fb4848ddf43be0af4db7.tar.gz | |
Adjust GFlow to apply at deepest ceiling instead of at max depth
This moves the point where GF_low applies up which implies that at all
shallower depth (i.e. during deco) a lower GF results which makes the deco
longer compared to the previous implementation.
Of course, "GF_low" applies at first deco stop is a bit tricky since the
depth of the first deco stop again depends on GF_low, i.e. there is
another equation to solve. You can do this by inverting the equation for
the ambient pressure and use GF_low as the gradient factor. This yields
amb = (b * M_value_corrected - GF_low * a * b) / ((1-b) * GF_low + b)
Signed-off-by: Robert C. Helling helling@atdotde.de
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
| -rw-r--r-- | deco.c | 12 |
1 files changed, 12 insertions, 0 deletions
@@ -81,6 +81,8 @@ const double buehlmann_He_factor_expositon_one_second[] = { #define N2_IN_AIR 0.7902 #define DECO_STOPS_MULTIPLIER_MM 3000.0 +#define GF_LOW_AT_MAXDEPTH 0 + double tissue_n2_sat[16]; double tissue_he_sat[16]; double tissue_tolerated_ambient_pressure[16]; @@ -96,6 +98,7 @@ static double tissue_tolerance_calc(const struct dive *dive) double gf_high = buehlmann_config.gf_high; double gf_low = buehlmann_config.gf_low; double surface = dive->surface_pressure.mbar / 1000.0; + double lowest_ceiling; for (ci = 0; ci < 16; ci++) { @@ -105,6 +108,13 @@ static double tissue_tolerance_calc(const struct dive *dive) /* tissue_tolerated_ambient_pressure[ci] = (tissue_inertgas_saturation - buehlmann_inertgas_a) * buehlmann_inertgas_b; */ +#if !GF_LOW_AT_MAXDEPTH + lowest_ceiling = (buehlmann_inertgas_b * tissue_inertgas_saturation - gf_low * buehlmann_inertgas_a * buehlmann_inertgas_b) / + ((1.0 - buehlmann_inertgas_b) * gf_low + buehlmann_inertgas_b); + if(lowest_ceiling > gf_low_pressure_this_dive) + gf_low_pressure_this_dive = lowest_ceiling; +#endif + tissue_tolerated_ambient_pressure[ci] = (-buehlmann_inertgas_a * buehlmann_inertgas_b * (gf_high * gf_low_pressure_this_dive - gf_low * surface) - (1.0 - buehlmann_inertgas_b) * (gf_high - gf_low) * gf_low_pressure_this_dive * surface + buehlmann_inertgas_b * (gf_low_pressure_this_dive - surface) * tissue_inertgas_saturation) / @@ -129,8 +139,10 @@ double add_segment(double pressure, struct gasmix *gasmix, int period_in_seconds double ppn2 = (pressure - WV_PRESSURE) * (1000 - fo2 - gasmix->he.permille) / 1000.0; double pphe = (pressure - WV_PRESSURE) * gasmix->he.permille / 1000.0; +#if GF_LOW_AT_MAXDEPTH if (pressure > gf_low_pressure_this_dive) gf_low_pressure_this_dive = pressure; +#endif if (ccpo2 > 0.0) { /* CC */ double rel_o2_amb, f_dilutent; |