On Sun, 2007-02-25 at 06:39 -0700, Dave Perry wrote: > On Sun, 2007-02-25 at 01:55 -0500, John Denker wrote: > > On 02/25/2007 12:30 AM, Dave Perry wrote: > > > The altitude capture in the current cvs kap140.nas used > > > > > > altFt = pressureAltitude + hpartial * (baroSetting - 29.92) > > > > > > and compared this to the target altitude. The problem with this is two > > > fold. The second term is a linear approximation to the > > > h(baroSetting,29.92). But h( , ) was the function before altAlert in > > > kap140.nas. It used two transcendental functions each frame and was not > > > the same function now used by John to model the atmosphere (close in the > > > troposphere, but not the same). > > > > By saving the result, you only need to do two transcendental > > functions every time the pilot changes the baro setting (not > > two per frame) which seems affordable. > > > The real issue here is that the function used is not the same function > that the altimeter is using.
I should have added that I cannot save the baro offset only when the baro setting changes in kap140.nas since the only access to _altimeter.kollsman_ft(baro_setting) is via altimeter.cxx and the property tree. We could check for changes in /autopilot/KAP140/settings/baro-setting-inhg and only change the baro offset node when baro-setting-inhg changes. Regards, -- Dave Perry ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Flightgear-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/flightgear-devel
