Calculation Method of Geographical Coordinate Distance between php Two Points

In this paper, we share the specific code of php to calculate the distance between two geographical coordinates for your reference. The specific contents are as follows

Function: Calculate the spherical distance between two points according to the pi and the radius coefficient of the earth and the latitude and longitude of the coordinates of two points.

Get the coordinate distance between two points:

<?php
/**
 *  Calculate the distance between two geographical coordinates 
 * @param Decimal $longitude1  Starting point longitude 
 * @param Decimal $latitude1  Starting point latitude 
 * @param Decimal $longitude2  End longitude  
 * @param Decimal $latitude2  Terminal latitude 
 * @param Int   $unit     Unit  1: Rice  2: Kilometres 
 * @param Int   $decimal   Precision   Retain decimal places 
 * @return Decimal
 */
function getDistance($longitude1, $latitude1, $longitude2, $latitude2, $unit=2, $decimal=2){

  $EARTH_RADIUS = 6370.996; //  Earth radius coefficient 
  $PI = 3.1415926;

  $radLat1 = $latitude1 * $PI / 180.0;
  $radLat2 = $latitude2 * $PI / 180.0;

  $radLng1 = $longitude1 * $PI / 180.0;
  $radLng2 = $longitude2 * $PI /180.0;

  $a = $radLat1 - $radLat2;
  $b = $radLng1 - $radLng2;

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

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

  return round($distance, $decimal);

}

//  Starting point coordinates 
$longitude1 = 113.330405;
$latitude1 = 23.147255;

//  End point coordinates 
$longitude2 = 113.314271;
$latitude2 = 23.1323;

$distance = getDistance($longitude1, $latitude1, $longitude2, $latitude2, 1);
echo $distance.'m'; // 2342.38m

$distance = getDistance($longitude1, $latitude1, $longitude2, $latitude2, 2);
echo $distance.'km'; // 2.34km

?>