some people were saying expr does internal double precision calculation, is it true? i dont think so...
2015-06-07 3:10 GMT-03:00 Cyrille Henry <c...@chnry.net>: > > > Le 07/06/2015 04:48, Max a écrit : > >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> Merci Cyrille, >> >> in the formula the intermediate steps are quite small fractions and it >> seems their precision is important. >> In the test case the Pd implementation is 8917.74 km off the proper >> result (2887.26). However I need a precision of about 1m. >> > i don't know how you get the 2887.26 km proper result : it's not the value > computed by the website you send (using value in the patch). > > >> So I assume the haversine formula is not implementable in Pd at all? >> (unless double precision will be there that is) >> >> Or is there a workaround? >> > > i'll thing about it. > cheers > > c > > > >> m. >> >> >> On 2015년 06월 07일 05:05, Cyrille Henry wrote: >> >>> hello, >>> >>> pow 2 did not like negative number. use "t f f" and "*" in order to >>> compute the square of a number. >>> >>> i correct 2 of your formula according to what i found in your >>> link. they both gives the same result : 11805 the same value >>> computed with your 2nd link gives 12210. for other value, it also >>> look close. so i guess the difference is number precision. >>> >>> >>> cheers c >>> >>> >>> >>> Le 06/06/2015 20:18, Max a écrit : >>> >>>> I tried to implement the Haversine formula in Pd which should >>>> give you the distance in km between two lat long coordinates. >>>> >>>> https://en.wikipedia.org/wiki/Haversine_formula >>>> http://www.movable-type.co.uk/scripts/latlong.html >>>> >>>> One huge obstacle is the imprecision of the 32bit floats, but >>>> even without that I can't get the formula to work. I kept 3 >>>> failed implementations in the test-case. >>>> >>>> http://rosettacode.org/wiki/Haversine_formula >>>> >>>> Could someone give me a hand please? >>>> >>>> >>>> >>>> _______________________________________________ >>>> Pd-list@lists.iem.at mailing list UNSUBSCRIBE and >>>> account-management -> >>>> http://lists.puredata.info/listinfo/pd-list >>>> >>>> >>> >>> _______________________________________________ >>> Pd-list@lists.iem.at mailing list UNSUBSCRIBE and >>> account-management -> http://lists.puredata.info/listinfo/pd-list >>> >>> >> -----BEGIN PGP SIGNATURE----- >> Version: GnuPG v1 >> >> iEYEARECAAYFAlVzsO0ACgkQ3EB7kzgMM6KETQCfRvgOmpqbmyhZaH2Y5hzsRHlC >> XOgAnR+6lqxJfjTj5k7vR747UU8ATrqA >> =pBZv >> -----END PGP SIGNATURE----- >> >> _______________________________________________ >> Pd-list@lists.iem.at mailing list >> UNSUBSCRIBE and account-management -> >> http://lists.puredata.info/listinfo/pd-list >> >> > _______________________________________________ > Pd-list@lists.iem.at mailing list > UNSUBSCRIBE and account-management -> > http://lists.puredata.info/listinfo/pd-list >
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