function round_1000(num)
{
return Math.floor((num + 0.0005) * 1000) / 1000;
}

function check_values()
{

var custom_URL = "http://www.skyandtelescope.com/observing/almanac/almanacCustom?";
var display_almanac;

var lat = parseFloat(document.observing.lat.value);
var lat_min = parseFloat(document.observing.latmin.value);
var lat_sgn = document.observing.latsgn.value;

var lng = parseFloat(document.observing.lng.value);
var lng_min = parseFloat(document.observing.lngmin.value);
var lng_sgn = document.observing.lngsgn.value;

var tzone = parseFloat(document.observing.tzone.value);

with (Math) {

lat = round_1000(lat + lat_min / 60);
lng = round_1000(lng + lng_min / 60);

if (lat_sgn == "S") {lat = lat * -1;}
if (lng_sgn == "E") {lng = lng * -1;}

if ((tzone > 0 && lng_sgn == "W") || (tzone < 0 && lng_sgn == "E"))
{
 alert("Please check that you have selected the correct time zone for your longitude. Time zones are positive east of Greenwich, negative if west.");
}
 else
{
custom_URL += "latitude=" + lat + "&";
custom_URL += "longitude=" + lng + "&";
custom_URL += "tzone=" + tzone + "&";
custom_URL += "UTdate=now&UTtime=now";
display_almanac = window.open(custom_URL,'chooser');
}

}
}

function getCookie( name )
{
  var start = document.cookie.indexOf( name + "=" );
  var len = start + name.length + 1;
  if ( ( !start ) && ( name != document.cookie.substring( 0, name.length ) ) ) {
    return null;
  }
  if ( start == -1 ) return null;
  var end = document.cookie.indexOf( ";", len );
  if ( end == -1 ) end = document.cookie.length;
  return unescape( document.cookie.substring( len, end ) );
}

function setCookie( name, value, expires, path, domain, secure )
{
  var today = new Date();
  today.setTime( today.getTime() );
  if ( expires ) {
    expires = expires * 1000 * 60 * 60 * 24;
  }
  var expires_date = new Date( today.getTime() + (expires) );
  document.cookie = name+"="+escape( value ) +
    ( ( expires ) ? ";expires="+expires_date.toGMTString() : "" ) + //expires.toGMTString()
    ( ( path ) ? ";path=" + path : "" ) +
    ( ( domain ) ? ";domain=" + domain : "" ) +
    ( ( secure ) ? ";secure" : "" );
}

function deleteCookie( name, path, domain )
{
  if ( getCookie( name ) ) document.cookie = name + "=" +
    ( ( path ) ? ";path=" + path : "") +
    ( ( domain ) ? ";domain=" + domain : "" ) +
    ";expires=Thu, 01-Jan-1970 00:00:01 GMT";
}

function load_saved()
{
var recall_custom_URL = "http://www.skyandtelescope.com/observing/almanac/almanacCustom?";
var show_saved_almanac;
var latitude_degrees = getCookie('almanac2latdeg');
var longitude_degrees = getCookie('almanac2longdeg');
var t_zone_hours = getCookie('almanac2tzonehours');

if (latitude_degrees == null && longitude_degrees == null)
{
 alert ("Sorry, but you haven't saved a previous location. Please choose a city from the Almanac's built-in gazetteer, or select a custom latitude, longitude and time zone from the pull-down menus. Once the Almanac is displayed you will have the option to save this information for future use.")
}
else
{
 recall_custom_URL += "latitude=" + latitude_degrees + "&";
 recall_custom_URL += "longitude=" + longitude_degrees + "&";
 recall_custom_URL += "tzone=" + t_zone_hours + "&";
 recall_custom_URL += "UTdate=now&UTtime=now";
 show_saved_almanac = window.open(recall_custom_URL,'chooser');
}
}