PHP calculates the distance between two points geographical coordinates

<code><span><span><?php</span><span>/**
 * 计算两点地理坐标之间的距离
 *<span> @param</span>  Decimal $longitude1 起点经度
 *<span> @param</span>  Decimal $latitude1  起点纬度
 *<span> @param</span>  Decimal $longitude2 终点经度 
 *<span> @param</span>  Decimal $latitude2  终点纬度
 *<span> @param</span>  Int     $unit       单位 1:米 2:公里
 *<span> @param</span>  Int     $decimal    精度 保留小数位数
 *<span> @return</span> Decimal
 */</span><span><span>function</span><span>getDistance</span><span>(<span>$longitude1</span>, <span>$latitude1</span>, <span>$longitude2</span>, <span>$latitude2</span>, <span>$unit</span>=<span>2</span>, <span>$decimal</span>=<span>2</span>)</span>{</span><span>$EARTH_RADIUS</span> = <span>6370.996</span>; <span>// 地球半径系数</span><span>$PI</span> = <span>3.1415926</span>;

    <span>$radLat1</span> = <span>$latitude1</span> * <span>$PI</span> / <span>180.0</span>;
    <span>$radLat2</span> = <span>$latitude2</span> * <span>$PI</span> / <span>180.0</span>;

    <span>$radLng1</span> = <span>$longitude1</span> * <span>$PI</span> / <span>180.0</span>;
    <span>$radLng2</span> = <span>$longitude2</span> * <span>$PI</span> /<span>180.0</span>;

    <span>$a</span> = <span>$radLat1</span> - <span>$radLat2</span>;
    <span>$b</span> = <span>$radLng1</span> - <span>$radLng2</span>;

    <span>$distance</span> = <span>2</span> * asin(sqrt(pow(sin(<span>$a</span>/<span>2</span>),<span>2</span>) + cos(<span>$radLat1</span>) * cos(<span>$radLat2</span>) * pow(sin(<span>$b</span>/<span>2</span>),<span>2</span>)));
    <span>$distance</span> = <span>$distance</span> * <span>$EARTH_RADIUS</span> * <span>1000</span>;

    <span>if</span>(<span>$unit</span>==<span>2</span>){
        <span>$distance</span> = <span>$distance</span> / <span>1000</span>;
    }

    <span>return</span> round(<span>$distance</span>, <span>$decimal</span>);

}

<span>// 起点坐标</span><span>$longitude1</span> = <span>113.330405</span>;
<span>$latitude1</span> = <span>23.147255</span>;

<span>// 终点坐标</span><span>$longitude2</span> = <span>113.314271</span>;
<span>$latitude2</span> = <span>23.1323</span>;

<span>$distance</span> = getDistance(<span>$longitude1</span>, <span>$latitude1</span>, <span>$longitude2</span>, <span>$latitude2</span>, <span>1</span>);
<span>echo</span><span>$distance</span>.<span>'m'</span>; <span>// 2342.38m</span><span>$distance</span> = getDistance(<span>$longitude1</span>, <span>$latitude1</span>, <span>$longitude2</span>, <span>$latitude2</span>, <span>2</span>);
<span>echo</span><span>$distance</span>.<span>'km'</span>; <span>// 2.34km</span><span>?></span></span></code>