/**
 * 計算兩個坐標之間的距離(米)
 * @param float $fP1Lat 起點(緯度)
 * @param float $fP1Lon 起點(經(jīng)度)
 * @param float $fP2Lat 終點(緯度)
 * @param float $fP2Lon 終點(經(jīng)度)
 * @return int
 */
function distanceBetween($fP1Lat, $fP1Lon, $fP2Lat, $fP2Lon){
    $fEARTH_RADIUS = 6378137;
    //角度換算成弧度
    $fRadLon1 = deg2rad($fP1Lon);
    $fRadLon2 = deg2rad($fP2Lon);
    $fRadLat1 = deg2rad($fP1Lat);
    $fRadLat2 = deg2rad($fP2Lat);
    //計算經(jīng)緯度的差值
    $fD1 = abs($fRadLat1 - $fRadLat2);
    $fD2 = abs($fRadLon1 - $fRadLon2);
    //距離計算
    $fP = pow(sin($fD1/2), 2) +
          cos($fRadLat1) * cos($fRadLat2) * pow(sin($fD2/2), 2);
    return intval($fEARTH_RADIUS * 2 * asin(sqrt($fP)) + 0.5);
}
/**
 * 百度坐標系轉(zhuǎn)換成標準GPS坐系
 * @param float $lnglat 坐標(如:106.426, 29.553404)
 * @return string 轉(zhuǎn)換后的標準GPS值:
 */
function BD09LLtoWGS84($fLng, $fLat){ // 經(jīng)度,緯度
    $lnglat = explode(',', $lnglat);
    list($x,$y) = $lnglat;
    $Baidu_Server = "http://api.map.baidu.com/ag/coord/convert?from=0&to=4&x={$x}&y={$y}";
    $result = @file_get_contents($Baidu_Server);
    $json = json_decode($result);
    if($json->error == 0){
        $bx = base64_decode($json->x);
        $by = base64_decode($json->y);
        $GPS_x = 2 * $x - $bx;
        $GPS_y = 2 * $y - $by;
        return $GPS_x.','.$GPS_y;//經(jīng)度,緯度
    }else
        return $lnglat;
}