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C++ to lisp

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pedroantonio123:
Hi

Can someone please help translate the  C ++ code in Lisp.
There is a code to go from UTM Coordinates to lang long.

Thanks for the Help

PedroAntonio


--- Code: --- public static void ToLatLon(double utmX, double utmY, string utmZone)
    {
        double latitude = 0;
        double longitude = 0;

        bool isNorthHemisphere = utmZone.Last() >= 'N';

        var diflat = -0.00066286966871111111111111111111111111;
        var diflon = -0.0003868060578;

        var zone = int.Parse(utmZone.Remove(utmZone.Length - 1));
        var c_sa = 6378137.000000;
        var c_sb = 6356752.314245;
        var e2 = Math.Pow((Math.Pow(c_sa, 2) - Math.Pow(c_sb, 2)), 0.5) / c_sb;
        var e2cuadrada = Math.Pow(e2, 2);
        var c = Math.Pow(c_sa, 2) / c_sb;
        var x = utmX - 500000;
        var y = isNorthHemisphere ? utmY : utmY - 10000000;

        var s = ((zone * 6.0) - 183.0);
        var lat = y / (6366197.724 * 0.9996); // Change c_sa for 6366197.724
        var v = (c / Math.Pow(1 + (e2cuadrada * Math.Pow(Math.Cos(lat), 2)), 0.5)) * 0.9996;
        var a = x / v;
        var a1 = Math.Sin(2 * lat);
        var a2 = a1 * Math.Pow((Math.Cos(lat)), 2);
        var j2 = lat + (a1 / 2.0);
        var j4 = ((3 * j2) + a2) / 4.0;
        var j6 = (5 * j4 + a2 * Math.Pow((Math.Cos(lat)), 2)) / 3.0; // saque a2 de multiplicar por el coseno de lat y elevar al cuadrado
        var alfa = (3.0 / 4.0) * e2cuadrada;
        var beta = (5.0 / 3.0) * Math.Pow(alfa, 2);
        var gama = (35.0 / 27.0) * Math.Pow(alfa, 3);
        var bm = 0.9996 * c * (lat - alfa * j2 + beta * j4 - gama * j6);
        var b = (y - bm) / v;
        var epsi = ((e2cuadrada * Math.Pow(a, 2)) / 2.0) * Math.Pow((Math.Cos(lat)), 2);
        var eps = a * (1 - (epsi / 3.0));
        var nab = (b * (1 - epsi)) + lat;
        var senoheps = (Math.Exp(eps) - Math.Exp(-eps)) / 2.0;
        var delt = Math.Atan(senoheps / (Math.Cos(nab)));
        var tao = Math.Atan(Math.Cos(delt) * Math.Tan(nab));

        longitude = (delt / Math.PI) * 180 + s;
        latitude = (((lat + (1 + e2cuadrada * Math.Pow(Math.Cos(lat), 2) - (3.0 / 2.0) * e2cuadrada * Math.Sin(lat) * Math.Cos(lat) * (tao - lat)) * (tao - lat))) / Math.PI) * 180; // era incorrecto el calculo

        Console.WriteLine("Latitud: " + latitude.ToString() + "\nLongitud: " + longitude.ToString());

    }

--- End code ---

Jeff H:
It looks like you have a C# snippet and not C++

irneb:

--- Quote from: Jeff H on December 01, 2014, 06:50:53 AM ---It looks like you have a C# snippet and not C++

--- End quote ---
Correct! That's definitely NOT C++. The use of var already shows something's different, if it was C++ (and only the newest C++) a similar idea would have used auto instead of var. But the clincher is the use of the Math library for the Pow method, if it was C++ it would have been a situation of adding a include clause for std::pow or math.h and then simply a function call to pow instead (not to mention if it was an object oriented library then it should have been Math->Pow instead of Math.Pow).

Anyhow, to get back to the OP's request, here's a start to show you the general idea of a direct translation:
--- Code - Auto/Visual Lisp: ---(defun ToLatLon (utmX utmY utmZone)  (setq latitude 0.0         longitude 0.0        isNorthHemisphere (wcmatch utmZone "*[Nn]")        diflat -0.00066286966871111111111111111111111111        diflon -0.0003868060578        zone (atoi (substr utmZone 1 (1- (strlen utm))))        c_sa 6378137.0        c_sb 6356752.314245        e2 (/ (expt (- (expt c_sa 2) (expt c_sb 2)) 0.5) c_sb)        ;; Carry on with same principles - the in-line maths are simply changed to polish notation  )  (princ "\nLatitud: ")  (princ latitude)  (princ "\nLongitud: ")  (princ longitude))Just carry on doing th exact same things for the other variables also.

Edit: Just to ensure your Lisp code doesn't screw up something else - you would need to localize those variables. For an explanation of how and why see Lee's tut on the subject: http://www.lee-mac.com/localising.html

And a quick way to get VLIDE to help you localize them: http://www.lee-mac.com/quicklocalising.html

CAB:
This may be of interest.
https://github.com/jl2/utm/

irneb:

--- Quote from: CAB on December 01, 2014, 09:09:39 AM ---This may be of interest.
https://github.com/jl2/utm/

--- End quote ---
Very nice! Not to mention it does the reverse also: LatLon->UTM.

Though it's written in Common Lisp. Some of those things aren't available for AutoLisp - I mean stuff like the setf and hash tables would need to be a setq (i.e. re-create the entire list each time instead of just setting an item in it) and a normal association list. But the rest should be easy to translate to AL as is.

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