Graph documentation [was: Re: Meaning of GF settings]
dirk at hohndel.org
Fri Jan 11 07:00:32 PST 2013
"Robert C. Helling" <helling at lmu.de> writes:
> On Fri, 11 Jan 2013, Dirk Hohndel wrote:
>> #define DIST_FROM_3_MTR 0.28
>> if (mydata.pressure > mydata.surface)
>> pressure = 3 * (unsigned int)((mydata.pressure - mydata.surface + DIST_FROM_3_MTR) / 0.3);
>> mydata.pressure = ((float)pressure)/10 + mydata.surface;
>> This clearly chops off the last bit of 'tail' in the shallow part. It's
>> not a lot (0.02 bar - about 20cm), but my guess is this helps to shorten
>> especially the last stop.
> I had to look at this for a while to understand what it's doing: It adds
> the pressure equivalent of 2.8m to mydata.pressure and then rounds to the
> next smaller multiple of 3m, i.e. depths 0-0.2m are rounded to 0 while
> 0.2m-3.2m are rounded to 3m, 3.2m-6.2m to 6m etc. So in effect it treats a
> ceiling (as mydata.pressure will later become the ceiling) of anything up
> to 20cm as 0. So, yes indeed, this is the "different way of rounding" that
> I was talking about.
> Do we want to do the same? We could equivalently always subtract 200mm
> from our ceiling ;-) Or at least for the planning part of the code.
Well... you are the Chief Scientist... :-)
But all kidding aside, I'm a bit nervous about this one. I think I'd
rather have us use the math as it is defined and have the people who
want to be more aggressive do so on their own.
More information about the subsurface