[PATCH 1/2] Calculate VPM-B ceiling outside of planner

[Rick Walsh]

Robert,

On 26 October 2015 at 09:06, Robert C. Helling <helling at atdotde.de> wrote:

> HI,
>
> On 25 Oct 2015, at 10:44, Rick Walsh <rickmwalsh at gmail.com> wrote:
>
> I like this concept.  I'm not sure how to turn it into something
> meaningful (other than the single statistic of "was the free gas volume
> more or less than permitted"), but it's worth discussing.
>
>
> as a first step in this direction, I added a number of printf’s to the
> VPM-B part. In particular, this displays the allowable (bottom) gradients
> for all compartments and for each iteration of the CVA how the volume of
> free gas compares to the critical value.
>

Much more efficient than setting breakpoints in gdb, and stepping through
one sample at a time (what I have been doing).

>
>
> This is of course not production code, it should not go into master. But
> for all those who want to understand VPM-B a but better, I pushed it to
> github. You can pull it form
>
> https://github.com/atdotde/subsurface.git analyze_vpm
>
> Have fun.
>
> What I learned so far: There are typically three rounds of the CVA: one
> with the vpmb_start_gradient, one with an updated gradient and then finally
> one with almost the same gradient again that results in the same run time.
> So it converges very fast in essentially one step of updating.
>
>
> So, using your observation that it converges fast, I realized we don't
actually need to calculate tts for every sample point.  We just need to
calculate tts for the final sample, iif the ceiling has been broken.  We
can then take deco_time = time from max ceiling depth until the ceiling
clears, or would have cleared.

See patches attached.  More testing is needed, and feedback welcome.

Rick
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.subsurface-divelog.org/pipermail/subsurface/attachments/20151026/b49e25c5/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-Calculate-VPM-B-ceiling-outside-of-planner.patch
Type: text/x-patch
Size: 9620 bytes
Desc: not available
URL: <http://lists.subsurface-divelog.org/pipermail/subsurface/attachments/20151026/b49e25c5/attachment.bin>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0002-Profile-Display-VPM-B-rather-than-GF-when-in-VPM-B-m.patch
Type: text/x-patch
Size: 5568 bytes
Desc: not available
URL: <http://lists.subsurface-divelog.org/pipermail/subsurface/attachments/20151026/b49e25c5/attachment-0001.bin>