You have a location expressed in degrees and minutes and you convert this to an expression in minutes. So try this:
0 60 #. _21 _57 _1317 The result of the inverse: 0 60 #: _1317 _22 3 And this is equal to the original: _22 3 =&(0 60&#.) _21 _57 1 Or: (3+_22*60)=_57+_21*60 1 For obtaining the original tuple you can use e.g.: (**0 60&#:@|)_1317 _21 _57 =@@i Hallo Björn Helgason, je schreef op 30-03-09 17:11: > I guess because this is base 60 that trying three 60 on the left is worth a > try > 60 60 60#:3849 > 1 4 9 > 60 60 60 #:_1317 > 59 38 3 > 60 60 60 #:1317 > 0 21 57 > > Still it is 21 57 and not _21 _57 as I started out with > > > 2009/3/30 Björn Helgason <[email protected]> > > >> One of the things I am trying to figure out is this conversion backI have >> >> LAT1=: 1r10800p1 * 60 #. 64 9 NB. Reykjavík >> LON1=: 1r10800p1 * 60 #. _21 _57 NB. Reykjavík >> >> Ok I take this here >> 60 #. _21 _57 >> 60 #. 64 9 >> 3849 >> 60 #. _21 _57 >> _1317 >> >> Now I want thew original back >> 180 60#:3849 >> 64 9 >> >> Fine and now the other one >> 90 60 #: _1317 >> 68 3 >> >> Not so fine I guess I have to subtract 90 and 60 >> 68 3-90 60 >> _22 _57 >> >> Close - should be _21 _57 >> Should I have subtracted 89 60? >> >> 68 3-89 60 >> _21 _57 >> >> >> 2009/3/29 Dan Baronet <[email protected]> >> >> Several years ago I wrote a navigation planner in J which included several >> >>> formulas for distance, heading determination, fuel consumption, etc. and I >>> used for years to travel. >>> Let me know if it can be of any use. >>> /D >>> >>> --- On Sun, 3/29/09, Björn Helgason <[email protected]> wrote: >>> >>> From: Björn Helgason <[email protected]> >>> Subject: Re: [Jprogramming] Finding GPS coordinates with J >>> To: "Programming forum" <[email protected]> >>> Date: Sunday, March 29, 2009, 9:36 AM >>> >>> I think I got the formula here so it is a question of translating it to J >>> and then to get the ring is to do the calculation for i.360 degrees and x >>> distance >>> >>> --------------------------------- >>> Formula: α = d/R (angular distance) >>> lat2 = lat1 + α.cos(θ) >>> Δφ = ln(tan(lat2/2+π/4)/tan(lat1/2+π/4)) >>> if E:W line q = cos(lat1) >>> otherwise q = Δlat/Δφ >>> Δlon = α.sin(θ)/q >>> lon2 = (lon1+Δlon+π) % 2.π − π >>> where ln is natural log and % is modulo, Δlon is taking shortest route >>> (<180°), and R is the earth’s radius >>> JavaScript: >>> lat2 = lat1 + d*Math.cos(brng); >>> var dPhi = >>> Math.log(Math.tan(lat2/2+Math.PI/4)/Math.tan(lat1/2+Math.PI/4)); >>> var q = (Math.abs(lat2-lat1) > 1e-10) ? (lat2-lat1)/dPhi : Math.cos(lat1); >>> var dLon = d*Math.sin(brng)/q; >>> // check for some daft bugger going past the pole, normalise latitude if >>> so >>> if (Math.abs(lat2) > Math.PI/2) lat2 = lat2>0 ? Math.PI-lat2 : >>> -(Math.PI-lat2); >>> lon2 = (lon1+dLon+Math.PI)%(2*Math.PI) - Math.PI; >>> >>> -------------------- >>> Formula: lat2 = asin(sin(lat1)*cos(d/R) + cos(lat1)*sin(d/R)*cos(θ)) >>> lon2 = lon1 + atan2(sin(θ)*sin(d/R)*cos(lat1), >>> cos(d/R)−sin(lat1)*sin(lat2)) >>> d/R is the angular distance (in radians), where d is the distance >>> travelled and R is the earth’s radius >>> JavaScript: >>> var lat2 = Math.asin( Math.sin(lat1)*Math.cos(d/R) + >>> Math.cos(lat1)*Math.sin(d/R)*Math.cos(brng) ); >>> var lon2 = lon1 + Math.atan2(Math.sin(brng)*Math.sin(d/R)*Math.cos(lat1), >>> Math.cos(d/R)-Math.sin(lat1)*Math.sin(lat2)); >>> Excel: lat2: =ASIN(SIN(lat1)*COS(d/ER) + COS(lat1)*SIN(d/ER)*COS(brng)) >>> lon2: =lon1 + ATAN2(COS(d/ER)-SIN(lat1)*SIN(lat2), >>> SIN(brng)*SIN(d/ER)*COS(lat1)) >>> --------------------------- >>> Trig functions take arguments in radians, so latitude, longitude, and >>> bearings in degrees >>> (either decimal or degrees/minutes/seconds) need to be converted to >>> radians, rad = π.deg/180. >>> When converting radians back to degrees (deg = 180.rad/π), West is >>> negative >>> if using signed >>> decimal degrees. For bearings, values in the range -π to +π [-180° to >>> +180°] >>> need to be converted >>> to 0 to +2π [0°–360°]; this can be done by (brng+2.π)%2.π [brng+360)%360] >>> where % is the modulo >>> operator. >>> >>> 2009/3/29 Björn Helgason <[email protected]> >>> >>> >>>> Thx >>>> I took a quick look at the links and it looks like there are good >>>> >>> formulas >>> >>>> available. >>>> I hope to get some time soon to translate them into J as I want. >>>> >>>> 2009/3/28 Brian Schott <[email protected]> >>>> >>>> Bjorn, >>>> >>>>> This search provides some good leads, I believe. >>>>> >>>>> >>>>> >>>>> >>> http://www.google.com/search?hl=en&client=safari&rls=en&q=distance%2Cbearing+sphere&btnG=Search >>> >>>>> -- >>>>> (B=) <-----my sig >>>>> Brian Schott >>>>> ---------------------------------------------------------------------- >>>>> For information about J forums see http://www.jsoftware.com/forums.htm >>>>> >>>>> >>>> -- >>>> Björn Helgason, Verkfræðingur >>>> Fugl&Fiskur ehf, >>>> Þerneyjarsundi 23, Hraunborgum >>>> Po Box 127,801 Selfoss , >>>> t-póst: [email protected] >>>> gsm: +3546985532 >>>> Landslags og skrúðgarðagerð, gröfuþjónusta >>>> http://groups.google.com/group/J-Programming >>>> >>>> >>>> Tæknikunnátta höndlar hið flókna, sköpunargáfa er meistari >>>> >>> einfaldleikans >>> >>>> góður kennari getur stigið á tær án þess að glansinn fari af skónum >>>> /|_ .-----------------------------------. >>>> ,' .\ / | Með léttri lund verður | >>>> ,--' _,' | Dagurinn í dag | >>>> / / | Enn betri en gærdagurinn | >>>> ( -. | `-----------------------------------' >>>> | ) | (\_ _/) >>>> (`-. '--.) (='.'=) ♖♘♗♕♔♙ >>>> `. )----' (")_(") ☃☠ >>>> >>>> >>> -- >>> Björn Helgason, Verkfræðingur >>> Fugl&Fiskur ehf, >>> Þerneyjarsundi 23, Hraunborgum >>> Po Box 127,801 Selfoss , >>> t-póst: [email protected] >>> gsm: +3546985532 >>> Landslags og skrúðgarðagerð, gröfuþjónusta >>> http://groups.google.com/group/J-Programming >>> >>> >>> Tæknikunnátta höndlar hið flókna, sköpunargáfa er meistari einfaldleikans >>> >>> góður kennari getur stigið á tær án þess að glansinn fari af skónum >>> /|_ .-----------------------------------. >>> ,' .\ / | Með léttri lund verður | >>> ,--' _,' | Dagurinn í dag | >>> / / | Enn betri en gærdagurinn | >>> ( -. | `-----------------------------------' >>> | ) | (\_ _/) >>> (`-. '--.) (='.'=) ♖♘♗♕♔♙ >>> `. )----' (")_(") ☃☠ >>> ---------------------------------------------------------------------- >>> For information about J forums see http://www.jsoftware.com/forums.htm >>> >>> >>> >>> ---------------------------------------------------------------------- >>> For information about J forums see http://www.jsoftware.com/forums.htm >>> >>> >> -- >> Björn Helgason, Verkfræðingur >> Fugl&Fiskur ehf, >> Þerneyjarsundi 23, Hraunborgum >> Po Box 127,801 Selfoss , >> t-póst: [email protected] >> gsm: +3546985532 >> Landslags og skrúðgarðagerð, gröfuþjónusta >> http://groups.google.com/group/J-Programming >> >> >> Tæknikunnátta höndlar hið flókna, sköpunargáfa er meistari einfaldleikans >> >> góður kennari getur stigið á tær án þess að glansinn fari af skónum >> /|_ .-----------------------------------. >> ,' .\ / | Með léttri lund verður | >> ,--' _,' | Dagurinn í dag | >> / / | Enn betri en gærdagurinn | >> ( -. | `-----------------------------------' >> | ) | (\_ _/) >> (`-. '--.) (='.'=) ♖♘♗♕♔♙ >> `. )----' (")_(") ☃☠ >> >> > > > > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
