依据经纬度计算距离的公式、百度坐标转换成GPS坐标(PHP版)

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;//经度,纬度 } else return $lnglat;}/**********************************************/function fn_rad($d){ return $d * pi() / 180.0;}// 2点间算法function P2PDistance($latlng1,$latlng2){ // 纬度1,经度1 ~ 纬度2,经度2 $latlng1 = explode(',',$latlng1); $latlng2 = explode(',',$latlng2); list($lat1,$lng1) = $latlng1; list($lat2,$lng2) = $latlng2; $EARTH_RADIUS = 6378.137; $radLat1 = fn_rad($lat1); $radLat2 = fn_rad($lat2); $a = $radLat1 - $radLat2; $b = fn_rad($lng1) - fn_rad($lng2); $s = 2 * asin(sqrt(pow(sin($a/2),2) + cos($radLat1)*cos($radLat2)*pow(sin($b/2),2))); $s = $s * $EARTH_RADIUS; $s = round($s * 10000) / 10000; return number_format($s,2);}echo '百度坐标: ',$lnglat,'

','转换后GPS坐标: ',FromBaiduToGpsXY($lnglat),'

';echo '转换前距离: ',P2PDistance('31.224286666667,121.420675','31.224665,121.437518'),'
';echo '转换后距离: ',P2PDistance('31.224286666667,121.420675','31.220157068379,121.42647022694');?>