quote:

---

Originally posted by Simon
it seems to be around 570miles

---

quote:

---

Originally posted by Simon
not very accurate and depending on which points you measure from and to it seems to be around 570miles

---

quote:

---

Originally posted by Ian
http://www.corsasport.co.uk/board/distance.php

From: TR12
To: KW1

Approximately: 945 km or 605 miles

Best thing to calibrate that map is to have postcodes on the coast and plot them while you're testing.

You could even cut out the member table all together and just plot the entire contents of your postcode table, just disable the image map bits first

---

quote:

---

Originally posted by Steve
I compare all my location by searching them up on multimap for comparison, do you think multimap is a good enough reference for that?

---

code:
LatLong.prototype.LatLongToOSGrid = function() {

  var a = 6377563.396, b = 6356256.910;              // Airy 1830 major & minor semi-axes

  var F0 = 0.9996012717;                             // NatGrid scale factor on central meridian

  var lat0 = 49*Math.PI/180, lon0 = -2*Math.PI/180;  // NatGrid true origin

  var N0 = -100000, E0 = 400000;                     // northing & easting of true origin, metres



  var e2 = 1 - (b*b)/(a*a);                          // eccentricity squared

  var n = (a-b)/(a+b), n2 = n*n, n3 = n*n*n;



  var lat = this.lat;

  var cosLat = Math.cos(lat), sinLat = Math.sin(lat);

  var nu = a*F0/Math.sqrt(1-e2*sinLat*sinLat);              // transverse radius of curvature

  var rho = a*F0*(1-e2)/Math.pow(1-e2*sinLat*sinLat, 1.5);  // meridional radius of curvature

  var eta2 = nu/rho-1;





  var Ma = (1 + n + (5/4)*n2 + (5/4)*n3) * (lat-lat0);

  var Mb = (3*n + 3*n*n + (21/8)*n3) * Math.sin(lat-lat0) * Math.cos(lat+lat0);

  var Mc = ((15/8)*n2 + (15/8)*n3) * Math.sin(2*(lat-lat0)) * Math.cos(2*(lat+lat0));

  var Md = (35/24)*n3 * Math.sin(3*(lat-lat0)) * Math.cos(3*(lat+lat0));

  var M = b * F0 * (Ma - Mb + Mc - Md);              // meridional arc



  var cos3lat = cosLat*cosLat*cosLat;

  var cos5lat = cos3lat*cosLat*cosLat;

  var tan2lat = Math.tan(lat)*Math.tan(lat);

  var tan4lat = tan2lat*tan2lat;



  var I = M + N0;

  var II = (nu/2)*sinLat*cosLat;

  var III = (nu/24)*sinLat*cos3lat*(5-tan2lat+9*eta2);

  var IIIA = (nu/720)*sinLat*cos5lat*(61-58*tan2lat+tan4lat);

  var IV = nu*cosLat;

  var V = (nu/6)*cos3lat*(nu/rho-tan2lat);

  var VI = (nu/120) * cos5lat * (5 - 18*tan2lat + tan4lat + 14*eta2 - 58*tan2lat*eta2);



  var dLon = this.lon-lon0;

  var dLon2 = dLon*dLon, dLon3 = dLon2*dLon, dLon4 = dLon3*dLon, dLon5 = dLon4*dLon, dLon6 = dLon5*dLon;



  var grid = new Object();

  grid.N = I + II*dLon2 + III*dLon4 + IIIA*dLon6;

  grid.E = E0 + IV*dLon + V*dLon3 + VI*dLon5;



  return LatLong.gridrefNumToLet(grid.E, grid.N, 8);

}

quote:

---

Originally posted by Steve
bought back my memories of GCSE maths

---