function OLatLng(lat, lon)
{
   this.lat = lat;
   this.lon = lon;
}

function WGS84LatLng(lat, lon)
{
	this.lat = lat;
	this.lon = lon;
}

function ONorthEast(east, north)
{
	this.north = north;
	this.east = east;
}

function ORect(bottomLeft, topRight)
{
	this.bl = bottomLeft;
	this.tr = topRight;
}

///////////////////////////////////////////////////////////////////////////////
//======================================================================
// based on jscalculators and Bill Chadwick code
//thank you all
// ======================================================================
var deg2rad = Math.PI / 180;
var rad2deg = 180.0 / Math.PI;
var pi = Math.PI;
var locres = 6; //locator characters


//===================================================================
//functions for myform2
//===================================================================
//===================================================================
function transform(lat, lon, a, e, h, a2, e2, xp, yp, zp, xr, yr, zr, s)
{
  // convert to cartesian; lat, lon are radians
  sf = s * 0.000001;
  v = a / (sqrt(1 - (e *(sin(lat) * sin(lat)))));
  x = (v + h) * cos(lat) * cos(lon);
  y = (v + h) * cos(lat) * sin(lon);
  z = ((1 - e) * v + h) * sin(lat);

  xrot = (xr / 3600) * deg2rad;
  yrot = (yr / 3600) * deg2rad;
  zrot = (zr / 3600) * deg2rad;

  hx = x + (x * sf) - (y * zrot) + (z * yrot) + xp;
  hy = (x * zrot) + y + (y * sf) - (z * xrot) + yp;
  hz = (-1 * x * yrot) + (y * xrot) + z + (z * sf) + zp;

  // Convert back to lat, lon
  lon = atan(hy / hx);
  p = sqrt((hx * hx) + (hy * hy));
  lat = atan(hz / (p * (1 - e2)));
  v = a2 / (sqrt(1 - e2 * (sin(lat) * sin(lat))));
  errvalue = 1.0;
  lat0 = 0;
  while (errvalue > 0.001)
  {
    lat0 = atan((hz + e2 * v * sin(lat)) / p);
    errvalue = abs(lat0 - lat);
    lat = lat0;
  }
  h = p / cos(lat) - v;

  return new OLatLng(lat, lon );
}
//===================================================================
function ll2ne(lat, lon, grid)
{
// converts Lat/Lon OSGB to Easting and Northing: inputs to radians.
  var phi = lat * deg2rad; // convert latitude to radians
  var lam = lon * deg2rad; // convert longitude to radians
 // grid = grid;       // British, Irish, Channel

  if (grid == "1")
  {
    a = 6377563.396;       // OSGB semi-major
    b = 6356256.91;        // OSGB semi-minor
    e0 = 400000;           // easting of false origin
    n0 = -100000;          // northing of false origin
    f0 = 0.9996012717;     // OSGB scale factor on central meridian
    e2 = 0.0066705397616;  // OSGB eccentricity squared
    lam0 = -0.034906585039886591;  // OSGB false east
    phi0 = 0.85521133347722145;    // OSGB false north

  }
  if (grid == "2")
  {
    a = 6377340.189;       // OSGBI semi-major
    b = 6356034.447;        // OSGBI semi-minor
    e0 = 200000;           // easting of false origin
    n0 = 250000;          // northing of false origin
    f0 = 1.000035;     // OSGBI scale factor on central meridian
    e2 = 0.00667054015;  // OSGBI eccentricity squared
    lam0 = -0.13962634015954636615389526147909;  // OSGBI false east
    phi0 = 0.93375114981696632365417456114141;    // OSGBI false north

  }
  if (grid == "3")
  {
    a = 6378388.000;       // INT24 ED50 semi-major
    b = 6356911.946;       // INT24 ED50 semi-minor
    e0 = 500000;           // easting of false origin
    n0 = 0;                // northing of false origin
    f0 = 0.9996;           // INT24 ED50 scale factor on central meridian
    e2 = 0.0067226700223333;  // INT24 ED50 eccentricity squared
    lam0 = -0.0523598775598;  // INT24 ED50 false east
    phi0 = 0 * deg2rad;    // INT24 ED50 false north

  }
  try{
  var af0 = a * f0;
  var bf0 = b * f0;

  // easting
  var slat2 = sin(phi) * sin(phi);
  var nu = af0 / (sqrt(1 - (e2 * (slat2))));
  var rho = (nu * (1 - e2)) / (1 - (e2 * slat2));
  var eta2 = (nu / rho) - 1;
  var p = lam - lam0; //LAM-LAM0
  var IV = nu * cos(phi);
  var clat3 = cos(phi) * cos(phi) * cos(phi);
  var tlat2 = tan(phi) * tan(phi);
  var V = (nu / 6) * clat3 * ((nu / rho) - tlat2);
  var clat5 = pow(cos(phi), 5);
  var tlat4 = pow(tan(phi), 4);
  var VI = (nu / 120) * clat5 * ((5 - (18 * tlat2)) + tlat4 + (14 * eta2) - (58 * tlat2 * eta2));
  east = e0 + (p * IV) + (pow(p, 3) * V) + (pow(p, 5) * VI);

  // northing
  var n = (af0 - bf0) / (af0 + bf0);
  var M = Marc(bf0, n, phi0, phi);
  var I = M + (n0);
  var II = (nu / 2) * sin(phi) * cos(phi);
  var III = ((nu / 24) * sin(phi) * clat3) * (5 - tlat2 + (9 * eta2));
  var IIIA = ((nu / 720) * sin(phi) * clat5) * (61 - (58 * tlat2) + tlat4);
  north = I + ((p * p) * II) + (pow(p, 4) * III) + (pow(p, 6) * IIIA);


  // make whole number values
  east = Math.round(east); // round to whole number of meters
  north = Math.round(north);
  }catch (e){
  }
  return new ONorthEast(east, north);
}
//===================================================================
function ne2ll(east, north, grid)  // (east, north, grid)
{
// converts NGR easting and nothing to lat, lon.
// input metres, output radians
  var nX = Number(north);
  var eX = Number(east);

  if (grid == 0)  // no grid specified
    grid = 1;  // default British

  // validate - check all are numbers and something is entered
  if ((String(nX) == "NaN") || (String(eX) == "NaN") || (north.length == 0) || (east.length == 0))
  {
    return;
  }

  if (grid == 2)  // Irish
  {
    a = 6377340.189;       // OSGBI semi-major
    b = 6356034.447;        // OSGBI semi-minor
    e0 = 200000;           // easting of false origin
    n0 = 250000;          // northing of false origin
    f0 = 1.000035;     // OSGBI scale factor on central meridian
    e2 = 0.00667054015;  // OSGBI eccentricity squared
    lam0 = -0.13962634015954636615389526147909;  // OSGBI false east
    phi0 = 0.93375114981696632365417456114141;    // OSGBI false north
  //  en2ngr(round(eX), round(nX), "2");
  }
   if (grid == 1)  // British
  {
    a = 6377563.396;       // OSI semi-major
    b = 6356256.91;        // OSI semi-minor
    e0 = 400000;           // easting of false origin
    n0 = -100000;          // northing of false origin
    f0 = 0.9996012717;     // OSI scale factor on central meridian
    e2 = 0.0066705397616;  // OSI eccentricity squared
    lam0 = -0.034906585039886591;  // OSI false east
    phi0 = 0.85521133347722145;    // OSI false north
    //en2ngr(round(eX), round(nX), "1");
  }
  if (grid == 3)   // Channel Is
  {
    a = 6378388.000;       // INT24 ED50 semi-major
    b = 6356911.946;       // INT24 ED50 semi-minor
    e0 = 500000;           // easting of false origin
    n0 = 0;                // northing of false origin
    f0 = 0.9996;           // INT24 ED50 scale factor on central meridian
    e2 = 0.0067226700223333;  // INT24 ED50 eccentricity squared
    lam0 = -0.0523598775598;  // INT24 ED50 false east
    phi0 = 0 * deg2rad;    // INT24 ED50 false north
    //en2ngr(round(eX), round(nX), "3");
  }
  var af0 = a * f0;
  var bf0 = b * f0;
  var n = (af0 - bf0) / (af0 + bf0);
  var Et = east - e0;
  var phid = InitialLat(north, n0, af0, phi0, n, bf0);
  var nu = af0 / (sqrt(1 - (e2 * (sin(phid) * sin(phid)))));
  var rho = (nu * (1 - e2)) / (1 - (e2 * (sin(phid)) * (sin(phid))));
  var eta2 = (nu / rho) - 1;
  var tlat2 = tan(phid) * tan(phid);
  var tlat4 = pow(tan(phid), 4);
  var tlat6 = pow(tan(phid), 6);
  var clatm1 = pow(cos(phid), -1);
  var VII = tan(phid) / (2 * rho * nu);
  var VIII = (tan(phid) / (24 * rho * (nu * nu * nu))) * (5 + (3 * tlat2) + eta2 - (9 * eta2 * tlat2));
  var IX = ((tan(phid)) / (720 * rho * pow(nu, 5))) * (61 + (90 * tlat2) + (45 * tlat4));
  var phip = (phid - ((Et * Et) * VII) + (pow(Et, 4) * VIII) - (pow(Et, 6) * IX));
  var X = pow(cos(phid), -1) / nu;
  var XI = (clatm1 / (6 * (nu * nu * nu))) * ((nu / rho) + (2 * (tlat2)));
  var XII = (clatm1 / (120 * pow(nu, 5))) * (5 + (28 * tlat2) + (24 * tlat4));
  var XIIA = clatm1 / (5040 * pow(nu, 7)) * (61 + (662 * tlat2) + (1320 * tlat4) + (720 * tlat6));
  var lambdap = (lam0 + (Et * X) - ((Et * Et * Et) * XI) + (pow(Et, 5) * XII) - (pow(Et, 7) * XIIA));

  var geo = convert_to_wgs(grid, phip, lambdap);

  var lat = geo.lat * rad2deg;
  var lon = geo.lon * rad2deg;

  return new OLatLng(lat, lon);
}
//===================================================================
function Marc(bf0, n, phi0, phi)
{
  var Marc = bf0 * (((1 + n + ((5 / 4) * (n * n)) + ((5 / 4) * (n * n * n))) * (phi - phi0))
    - (((3 * n) + (3 * (n * n)) + ((21 / 8) * (n * n * n))) * (sin(phi - phi0)) * (cos(phi + phi0)))
    + ((((15 / 8) * (n * n)) + ((15 / 8) * (n * n * n))) * (sin(2 * (phi - phi0))) * (cos(2 * (phi + phi0))))
    - (((35 / 24) * (n * n * n)) * (sin(3 * (phi - phi0))) * (cos(3 * (phi + phi0)))));
  return(Marc);
}
//===================================================================
function InitialLat(north, n0, af0, phi0, n, bf0)
{
  var phi1 = ((north - n0) / af0) + phi0;
  var M = Marc(bf0, n, phi0, phi1);
  var phi2 = ((north - n0 - M) / af0) + phi1;
  var ind = 0;
  while ((abs(north - n0 - M) > 0.00001) && (ind < 20))  // max 20 iterations in case of error
  {
	ind = ind + 1;
	phi2 = ((north - n0 - M) / af0) + phi1;
    M = Marc(bf0, n, phi0, phi2);
    phi1 = phi2;
  }
  return(phi2);
}
//===================================================================
function choose_where(lat, lon)
{
var where = "";
if ((lat >= 49) && (lat <= 50) && (lon >= -3) && (lon <= -2))
  where = "3"
else if ((lon <= -6) && (lon > -11) && (lat > 51.242) && (lat <= 54))
  where = "2";
else if ((lon < -5.333) && (lon >- 11) && (lat >= 54) && (lat <= 55))
  where = "2";
else if ((lon < -5.9) && (lon >= -9) && (lat >= 55) && (lat < 55.5))
  where = "2";
else if ((lon < 1.8) && (lon > -9) && (lat > 49.8166) && (lat < 61))
  where = "1";
return where;
}

function todms(lat, lon)
// convert decimal degrees to dms
{
  var latbrg = 1;
  var lonbrg = 2;
  if (lat < 0)
    latbrg = 2
  if (lon < 0)
    lonbrg = 1;
  var tlat = abs(lat);
  var tlon = abs(lon);
  var deglat = floor(tlat);
  var t = (tlat - deglat) * 60;
  var minlat = floor(t);
  var seclat = (t - minlat) * 60;
  seclat = seclat + 0.005;  //round to .005 sec
  seclat = floor(seclat * 100) / 100;  //  works in js 1.4
  var deglon = floor(tlon);
  t = (tlon - deglon) * 60;
  var minlon = floor(t);
  var seclon = (t - minlon) * 60;
  seclon = seclon + 0.005;
  seclon = floor(seclon * 100) /100;  // js 1.4

}
//===================================================================
function convert_to_wgs(grid, phip, lambdap)
{
  var WGS84_AXIS = 6378137;
  var WGS84_ECCENTRIC = 0.00669438037928458;
  var OSGB_AXIS = 6377563.396;
  var OSGB_ECCENTRIC = 0.0066705397616;
  var IRISH_AXIS = 6377340.189;
  var IRISH_ECCENTRIC = 0.00667054015;
  var INT24_AXIS = 6378388.000;
  var INT24_ECCENTRIC = 0.0067226700223333;
  var height = 10;  // dummy height
  var geo = null;
  if (grid == 1)
  {
    geo = transform(phip, lambdap, OSGB_AXIS, OSGB_ECCENTRIC, height, WGS84_AXIS, WGS84_ECCENTRIC, 446.448, -125.157, 542.06, 0.1502, 0.247, 0.8421, 20.4894);
  }
  if (grid == 2)
  {
    geo = transform(phip, lambdap, IRISH_AXIS, IRISH_ECCENTRIC, height, WGS84_AXIS, WGS84_ECCENTRIC, 482.53, -130.596, 564.557, -1.042, -0.214, -0.631, -8.15);
  }
  if (grid == 3)
  {
    geo = transform(phip, lambdap, INT24_AXIS, INT24_ECCENTRIC, height,  WGS84_AXIS, WGS84_ECCENTRIC, -83.901, -98.127, -118.635, 0, 0, 0, 0);
  }
  return(geo);
}
function convert_to_ogb(grid, phip, lambdap)
{
  var WGS84_AXIS = 6378137;
  var WGS84_ECCENTRIC = 0.00669438037928458;
  var OSGB_AXIS = 6377563.396;
  var OSGB_ECCENTRIC = 0.0066705397616;
  var IRISH_AXIS = 6377340.189;
  var IRISH_ECCENTRIC = 0.00667054015;
  var INT24_AXIS = 6378388.000;
  var INT24_ECCENTRIC = 0.0067226700223333;
  var height = 0;  // dummy height
  var geo = null;
  if (grid == 1)
  {
    geo = transform(phip, lambdap, WGS84_AXIS, WGS84_ECCENTRIC , height, OSGB_AXIS, OSGB_ECCENTRIC, -446.448, 125.157, -542.06, -0.1502, -0.247, -0.8421, 20.4894);
  }
  if (grid == 2)
  {
    geo = transform(phip, lambdap, WGS84_AXIS, WGS84_ECCENTRIC , height, IRISH_AXIS, IRISH_ECCENTRIC, -482.53, 130.596, -564.557, 1.042, 0.214, 0.631, -8.15);
  }
  if (grid == 3)
  {
    geo = transform(phip, lambdap, WGS84_AXIS, WGS84_ECCENTRIC , height,  INT24_AXIS, INT24_ECCENTRIC, 83.901, 98.127, 118.635, 0, 0, 0, 0);
  }
  return(geo);
}

//===================================================================
function en2ngr(east, north, grid)
{
  var nstr = String(north);
  var estr = String(east);
  while (nstr.length < 6) {nstr = "0" + nstr };
  while (estr.length < 6) {estr = "0" + estr };

  if (grid == "3")
  {

    if (north > 5500000)
    {
      var ngr = "WA " + estr.substring(1, 7) + " " + nstr.substring(2, 7);

    }
    else if (north < 5500000)
    {
      var ngr = "WV " + estr.substring(1, 7) + " " + nstr.substring(2, 7);

    }
  }

  if ((grid == "1") || (grid == "2"))
  {
    var eX = east / 500000;
    var nX = north / 500000;
    var tmp = floor(eX)-5.0 * floor(nX)+17.0;
    nX = 5 * (nX - floor(nX));
    eX = 20 - 5.0 * floor(nX) + floor(5.0 * (eX - floor(eX)));
    if (eX > 7.5)
      eX = eX + 1;
    if (tmp > 7.5)
      tmp = tmp + 1;
    var eing = estr;
    var ning = nstr;

    var l = eing.length;
    eing = eing.substring(l - 5, l);
    l = ning.length;
    ning = ning.substring(l - 5, l);
    ngr = chr(tmp + 65) + chr(eX + 65) + " " + eing + " " + ning;
  }

  if (grid == "2")
  {
    l = ngr.length;
    ngr = ngr.substring(1, l);
  }

  return ngr;
}

//===================================================================
function conv_ngr_to_ings(ngr, grid)
{
  var ngr = ngr.toUpperCase();
  var lenngr = ngr.length;

  var i = 0;
  var t = "";

  // replace spaces
  while(i < lenngr)
  {
    if (ngr.charAt(i) != " ")
      t = t + ngr.charAt(i);
  i++;
  }

  // check length, then add leading space if odd - Irish?
  lenngr = t.length;
  if (lenngr >12)
  {
    return;
  }

  var temp = round(lenngr/2)*2;
  if (lenngr != temp)
    ngr = " " + t;  // possible Irish NGR
  else
    ngr = t;

  // now format to 12 digits
  if (ngr.length == 4)
    t = ngr.substring(0,3) + "5000" + ngr.substring(3) + "5000";
  if (ngr.length == 6)
    t = ngr.substring(0,4) + "000" + ngr.substring(4) + "000";
  if (ngr.length == 8)
    t = ngr.substring(0,5) + "00" + ngr.substring(5) + "00";
  if (ngr.length == 10)
    t = ngr.substring(0,6) + "0" + ngr.substring(6) + "0";
  if (ngr.length == 12)
    t = ngr;
  ngr = t;

  // check ngr has two letters and 10 numbers
  var myRegExp = /[ A-Z]{2}[0-9]{10}/;
  if (! myRegExp.test(ngr))
  {
    return;
  }

  if (grid == "3")
  {
    var eci = "5" + ngr.substring(2,7);
    if (ngr.charAt(1) == "V")
      var nci = "54" + ngr.substring(7,12);
    else
      var nci = "55" + ngr.substring(7,12);
    var east = Number(eci);
    var north = Number(nci);
  }
  if ((grid == "1") || (grid == "2"))
  {
    var irish = 0;  //not Irish
    var north = Number(ngr.substring(7));
    var east = Number(ngr.substring(2,7));

    var t1 = ngr.charCodeAt(0) - 65;
    if (t1 < 0)
    {
      t1 = 18;    // S for Irish 83-65
      irish = 1;
    }

    if (t1 > 8)
      t1 = t1 -1;
    var t2 = floor(t1 / 5);
    north = north + 500000 * (3 - t2);
    east = east + 500000 * (t1 - 5 * t2 - 2);

    t1 = ngr.charCodeAt(1) - 65;
    if (t1 > 8)
      t1 = t1 - 1;
    t2 = floor(t1 / 5);
    north = north + 100000 * ( 4 - t2);
    east = east + 100000 * ( t1 - 5 * t2);
  }
  return new ONorthEast(east, north);

}

function ngr2wgs(ngr, grid){
  var ings = conv_ngr_to_ings(ngr, grid);
  var ll = ne2ll(ings.east, ings.north, grid);

  return ll;

}

//
//convert WGS84 Latitude and Longitude to Ordnance Survey 1936 Latitude Longitude

function wgs2ogb(WGlat, WGlon, grid)
{
  //first off convert to radians
  var radWGlat = WGlat * deg2rad;
  var radWGlon = WGlon * deg2rad;

  var geo = convert_to_ogb(grid, radWGlat, radWGlon);
  //convert back to degrees
  var newLat = geo.lat * rad2deg;
  var newLon = geo.lon * rad2deg;

  return new OLatLng(newLat, newLon);

}


//convert Ordnance Survey 1936 Latitude Longitude to WGS84 Latitude and Longitude
function ogb2wgs(OGlat, OGlon, grid)
{
  //first off convert to radians
  var radOGlat = OGlat * deg2rad;
  var radOGlon = OGlon * deg2rad;

  var geo = convert_to_wgs(grid, radOGlat, radOGlon);
  //convert back to degrees
  var newLat = geo.lat * rad2deg;
  var newLon = geo.lon * rad2deg;

  return new WGS84LatLng(newLat, newLon);

}

//return rect in OSGB N/E coords that encloses the given wgs84 rect
function enclosingOsgbRect(WGleft,WGbottom,WGtop,WGright, grid){

	var blOGB = wgs2ogb(WGbottom,WGleft,grid);
	var trOGB = wgs2ogb(WGtop,WGright,grid);
	var brOGB = wgs2ogb(WGbottom,WGright,grid);
	var tlOGB = wgs2ogb(WGtop,WGleft,grid);

	var blEN = ll2ne(blOGB.lat,blOGB.lon,grid);
	var trEN = ll2ne(trOGB.lat,trOGB.lon,grid);
	var brEN = ll2ne(brOGB.lat,brOGB.lon,grid);
	var tlEN = ll2ne(tlOGB.lat,tlOGB.lon,grid);

	var e = Math.min(blEN.east,tlEN.east);
	var w = Math.max(brEN.east,trEN.east);
	var s = Math.min(blEN.north,brEN.north);
	var n = Math.max(trEN.north,tlEN.north);

	return new ORect(new ONorthEast(e,s),new ONorthEast(w,n));
}


//===================================================================


// Maths functions

function mod(y, x)
{
if (y >= 0)
  return y - x * floor(y / x);
else
  return y + x * (floor(-y / x) + 1.0);
}

function atan2(y, x)
{
	return Math.atan2(y, x);
}

function sqrt(x)
{
	return Math.sqrt(x);
}

function tan(x)
{
	return Math.tan(x);
}

function sin(x)
{
	return Math.sin(x);
}

function cos(x)
{
	return Math.cos(x);
}

function acos(x)
{
	return Math.acos(x);
}

function floor(x)
{
	return Math.floor(x);
}

function round(x)
{
	return Math.round(x);
}

function ceil(x)
{
	return Math.ceil(x)
}

function ln(x)
{
	return Math.log(x);
}

function abs(x)
{
	return Math.abs(x);
}

function pow(x, y)
{
	return Math.pow(x, y);
}

function atan(x)
{
	return Math.atan(x);
}

function chr(x)
{
return String.fromCharCode(x);
}

function round(x)
{
	return Math.round(x);
}