Thx for this explanation 2009/3/31 Aai <[email protected]>
> 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 > -- 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
