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Re: [gpsd-dev] ✘CEP(50) 0.285 meters

From: Gary E. Miller
Subject: Re: [gpsd-dev] ✘CEP(50) 0.285 meters
Date: Sat, 23 Jul 2016 17:37:01 -0700

Yo Fred!

On Sat, 23 Jul 2016 13:01:46 -0700 (PDT)
Fred Wright <address@hidden> wrote:

> Restoring the original subject (with cleanup).  Sorry about the
> earlier subject change; I thought Pine was smart enough not to do
> that when the subjects were identical (or maybe they weren't
> identical due to the funny characters), but didn't check.

Pine?  I used to love pine, but it has not had a patch in over 10
years..  And those funny chars are called UTF-8.  It is all the rage
this millennium.

> > PRIu64 :-)  Agreed, but to write portable code with fixed-width
> > types, one basicallyy has to use the PRI specifiers.  It's a little
> > ugly, but not hard.  
> I wasn't aware of that, although I have created something similar on
> occasion.  But it's *way* ugly and verbose, seriously impairing
> readability.

When push comes to shove, functionality trumps readability.

When doing high precision you gotta force the integer/float types
to what you need.

> BTW, if the only purpose is to calculate GPS error bounds, then scaled
> Pythagoras is perfectly adequate.  If the fixes are so badly scattered
> that it isn't adequate, then the GPS is severely impaired. :-)

The problem at hand is scatter plots, which are usually for 100
meters or less.  I'm gonna use Hal's idea rip out the transcendantals
(which are blowing up) and use the small angle approximations, which
are actually more accurate than the "proper" math.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

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