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<div class="moz-cite-prefix">On 2019/08/10 15:40, Robert Helling
wrote:<br>
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cite="mid:1FF5AA22-D492-4E2F-968D-0BFF420134A0@atdotde.de">
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Willem,<br class="">
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<div class="">On 10. Aug 2019, at 15:19, Robert Helling <<a
href="mailto:helling@atdotde.de" class=""
moz-do-not-send="true">helling@atdotde.de</a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class=""><span style="caret-color: rgb(0, 0, 0);
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!important;" class="">PS: The original problem arose as
the interpolated table value is used in the denominator of
the cns += formula and would result in a pole when the
extrapolated table value reaches 0. Maybe we should redo
the whole thing and linearly interpolate the inverses of
the table value rather than the table value. For those an
extrapolation would be more sensible.</span></div>
</blockquote>
</div>
<br class="">
<div class="">here is another idea: With the exception of the
values above pO2 of 1.5bar, a power law is actually a pretty
good fit to the table:</div>
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<div class="">This is exp(11.7853 - 0.00193873 pO2).</div>
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<div class="">Maybe, we should give up the idea of the table
entirely and use this power law instead?</div>
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<div class="">Best</div>
<div class="">Robert</div>
</blockquote>
<p>An interesting alternative, Robert. I am not happy with the
deviation at 1.5 and 1.6. One would have to check what the effect
of these two points are on the power curve. What is the effect on
the overall fit of the power curve if one omits those two points?
What of a 3rd order polynomial that could in principle accommodate
the inflection at 1.4? I am not averse to a mathematical solution
because the linear interpolation also causes some inaccuracy.</p>
<p>And of course I like your graph because it is the right way round
with time limit being the dependent variable. Baker's graph is the
wrong way round.</p>
<p>I would also love to see what it will look like if one
interpolates on inverses. But it does not in principle avoid the
problem at pO2=1.65.</p>
<p>With respect to your idea of NOT calculating CNS when pO2 >
1.65, if I understand you correctly, the underestimate will be
much higher if those points on the dive profile do not contribute
to the total CNS toxicity. I think in the planner the solution is
to incorporate whatever mechanism appears prudent and simply add a
warning to the dive plan that the CNS value cannot be trusted
because of the high pO2. In the dive log it is a different thing
since the dive log has no way of adding system warnings except for
the red banner at the bottom of the screen. I am not sure that a
user would like to get past a red banner warning every time she/he
views that dive.<br>
</p>
<p>Kind regards,</p>
<p>willem</p>
<p><br>
</p>
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