<?php

function ($params, $di) {

    $lat1 = $params['lat1'];

    $lat2 = $params['lat2'];

    $lng2 = $params['lng2'];

    $lat2 = $params['lat2'];

    // 地球半径(单位：千米)

    $r = 6378.137; 

    // 将角度转为狐度

    $radLat1 = deg2rad($lat1); //deg2rad()函数将角度转换为弧度

    $radLat2 = deg2rad($lat2);

    $radLng1 = deg2rad($lng1);

    $radLng2 = deg2rad($lng2);

    $a = $radLat1 - $radLat2;

    $b = $radLng1 - $radLng2;

    $s = 2 * asin(sqrt(pow(sin($a / 2), 2) + cos($radLat1) * cos($radLat2) * pow(sin($b / 2), 2)));

    // 计算距离，并换算成米

    $s = $s * $r * 1000;

    return ['distance' => $s];

​

}