// extend Number object with methods for presenting bearings & lat/longs

String.prototype.parseDeg = function() {
  if (!isNaN(this)) return Number(this);                 // signed decimal degrees without NSEW

  var degLL = this.replace(/^-/,'').replace(/[NSEW]/i,'');  // strip off any sign or compass dir'n
  var dms = degLL.split(/[^0-9.]+/);                     // split out separate d/m/s
  for (var i in dms) if (dms[i]=='') dms.splice(i,1);    // remove empty elements (see note below)
  switch (dms.length) {                                  // convert to decimal degrees...
    case 3:                                              // interpret 3-part result as d/m/s
      var deg = dms[0]/1 + dms[1]/60 + dms[2]/3600; break;
    case 2:                                              // interpret 2-part result as d/m
      var deg = dms[0]/1 + dms[1]/60; break;
    case 1:                                              // decimal or non-separated dddmmss
      if (/[NS]/i.test(this)) degLL = '0' + degLL;       // - normalise N/S to 3-digit degrees
      var deg = dms[0].slice(0,3)/1 + dms[0].slice(3,5)/60 + dms[0].slice(5)/3600; break;
    default: return NaN;
  }
  if (/^-/.test(this) || /[WS]/i.test(this)) deg = -deg; // take '-', west and south as -ve
  return deg;
}

Number.prototype.toDMS = function() {  // convert numeric degrees to deg/min/sec
  var d = Math.abs(this);  // (unsigned result ready for appending compass dir'n)
  d += 1/7200;  // add  second for rounding
  var deg = Math.floor(d);
  var min = Math.floor((d-deg)*60);
  var sec = Math.floor((d-deg-min/60)*3600);
  // add leading zeros if required
  if (deg<100) deg = '0' + deg; if (deg<10) deg = '0' + deg;
  if (min<10) min = '0' + min;
  if (sec<10) sec = '0' + sec;
  return deg + '\u00B0' + min + '\u2032' + sec + '\u2033';
}

Number.prototype.toLat = function() {  // convert numeric degrees to deg/min/sec latitude
  return this.toDMS().slice(1) + (this<0 ? 'S' : 'N');  // knock off initial '0' for lat!
}

Number.prototype.toLon = function() {  // convert numeric degrees to deg/min/sec longitude
  return this.toDMS() + (this>0 ? 'E' : 'W');
}

Number.prototype.toPrecision = function(fig) {  // override toPrecision method with one which displays 
  if (this == 0) return 0;                      // trailing zeros in place of exponential notation
  var scale = Math.ceil(Math.log(this)*Math.LOG10E);
  var mult = Math.pow(10, fig-scale);
  return Math.round(this*mult)/mult;
}

function toDegrees(lat1) {
	return lat1.parseDeg().toDMS();
}