[ gpsdrive ] No developer question, but a question about an older version of gpsdrive

[Sascha Silbe]

On Sun, Nov 04, 2007 at 01:05:26AM +0100, Thomas Schönhütl wrote:

#define ROUTEREACH 
(((1/600)*groundspeed*groundspeed+(1/20)*groundspeed+(25/3))*groundspeed/(3600*milesconv)) 


#define ROUTEREACH 
(((1/42000)*groundspeed*groundspeed*groundspeed-(1/280)*groundspeed*groundspeed+(44/105)*groundspeed)*groundspeed/(3600*milesconv)) 


> - I doubled the ROUTEREACH and recompiled gpsdrive
> - then I did the same run and now the result was nearly PERFECT!!!
In the SVN version, current.groundspeed is a floating-point number. 
Perhaps it's an integer in the older version? In that case the cubic 
part could overflow, giving you nonsense as result. You could try 
writing "(double)" (including the parentheses, but not the quotation 
marks) before each "groundspeed".
You could also add a printf() call to output groundspeed and ROUTEREACH, 
so we could should whether it's in the calculation or somewhere else.

CU Sascha

-- 
http://sascha.silbe.org/
http://www.infra-silbe.de/
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