/**
 * @param point   Center point in google.maps.LatLng
 * @param radius  Rarius of circle in km (1km = 0.6214 miles)
 * @param color   param to google.maps.Polyline (omissible)
 * @param weight  param to google.maps.Polyline (omissible)
 * @param opacity param to google.maps.Polyline (omissible)
 * @return google.maps.Polyline
 */
function pseudoGCircle(point, radius, color, weight, opacity) {
    var vertex = 360;
    var EquatorialRadius = 6378137; // WGS-84
    var F = 298.257223563;          // Inverse of Flattening: 1/f (WGS-84)

    // Squared Earth's eccentricity:
    // E = e^2 = 2*f - f^2 = (2*F - 1) / F^2
    var E = ((2 * F) -1) / Math.pow(F, 2);

    // Pi times the Equatorial Radius
    var PI_ER = Math.PI * EquatorialRadius;

    // 1 - e2 sin2(θ)
    var TMP = 1 - E * Math.pow(Math.sin(point.latRadians()), 2);

    // Length (m) of one degrees of latitude
    var arc_lat = (PI_ER * (1 - E)) / (180 * Math.pow(TMP, 3/2)); 

    // Length (m) of one degrees of longitude
    var arc_lng = (PI_ER * Math.cos(point.latRadians())) / (180 * Math.pow(TMP, 1/2)); 

    // Radius (m)
    var R = radius * 1000;

    var points = new Array(vertex);
    for (i = 0; i <= vertex; i++) {
        var rad = (i / (vertex / 2)) * Math.PI;
        var lat = (R / arc_lat) * Math.sin(rad) + point.lat();
        var lng = (R / arc_lng) * Math.cos(rad) + point.lng();
        points[i] = new google.maps.LatLng(lat, lng);
    }
    return new google.maps.Polyline(points, color, weight, opacity);
}

var circle = pseudoGCircle(new google.maps.LatLng(37.4419, -122.1419), 1);

map = new google.maps.Map2(document.getElementById("map"));
map.addOverlay(circle);

/**
 * @param point   Center point in google.maps.LatLng
 * @param radius  Rarius of circle in km
 * @param color   param to google.maps.Polyline (omissible)
 * @param weight  param to google.maps.Polyline (omissible)
 * @param opacity param to google.maps.Polyline (omissible)
 * @return google.maps.Polyline
 */
function pseudoGCircle(point, radius, color, weight, opacity) {
    var vertex = 360;
    var TMP = 1 - E * Math.pow(Math.sin(point.latRadians()), 2);
    var A = 110574.27582159444444444444444444; // (PI_ER * (1 - E)) / 180
    var B = 111319.49079327333333333333333333; // PI_ER / 180
    var arc_lat = A / Math.pow(TMP, 3/2);
    var arc_lng = (B * Math.cos(point.latRadians())) / Math.pow(TMP, 1/2);
    var R = radius * 1000;
    var points = new Array(vertex);
    for (i = 0; i <= vertex; i++) {
        var rad = (i / (vertex / 2)) * Math.PI;
        var lat = (R / arc_lat) * Math.sin(rad) + point.lat();
        var lng = (R / arc_lng) * Math.cos(rad) + point.lng();
        points[i] = new google.maps.LatLng(lat, lng);
    }
    return new google.maps.Polyline(points, color, weight, opacity);
}

var circle = pseudoGCircle(new google.maps.LatLng(37.4419, -122.1419), 1);

map = new google.maps.Map2(document.getElementById("map"));
map.addOverlay(circle);