Typo in CNS calculation
deanmurray1 at gmail.com
Sat Aug 10 03:12:13 PDT 2019
Shearwater published their approach for po2 > 1.6. Seems pretty
conservative and given their position in the market I suspect it would be
pretty agreeable to most people to follow their lead.
On Sat, 10 Aug. 2019, 6:30 pm Willem Ferguson, <
willemferguson at zoology.up.ac.za> wrote:
> On 2019/08/09 23:23, Robert Helling wrote:
> could you please have a look at the final computation in static double
> calculate_cns_dive(const struct dive *dive)
> in divelist.c
> It seems to me that the first minus in
> cns += (double)t / ((double)cns_table[j][SINGLE_EXP] - ((double)po2i - (double)cns_table[j][PO2VAL]) * (double)cns_table[j][SINGLE_SLOPE] / 10.0) * 100;
> should be plus (at least according to the formula in the comment above. At least, with this minus, you get negative CNS values for a planned air dive to 80m of depth.
> The reason for the negative value is because the dive plan involves pO2
> values above 1.6bar (EAN38 at 35m=pO2 of 1.7bar). The NOAA tables do not
> provide values above pO2 = 1.6.
> I am working on a sensible solution because we need a sensible approach
> for this use case.
> Kind regards,
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> Please refer to
> http://upnet.up.ac.za/services/it/documentation/docs/004167.pdf for full
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