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
