distance calculations using Spherical Law of Cosines and Haversine Formula

distances_slc_haversine.php

<?php

# Spherical Law of Cosines
function distance_slc($lat1, $lon1, $lat2, $lon2) {
    $a = sin(deg2rad($lat1)) * sin(deg2rad($lat2));
    $b = cos(deg2rad($lat1)) * cos(deg2rad($lat2));
    $c = cos(deg2rad($lon2 - $lon1));
    $distance = rad2deg(acos($a + $b * $c));
    return round($distance * 60 * 1.1515, 4);
}

# Haversine Formula
function distance_haversine($lat1, $lon1, $lat2, $lon2) {
    $a = pow(sin(deg2rad(($lat2 - $lat1) / 2)), 2);
    $b = pow(cos(deg2rad($lat1)), 2);
    $c = pow(sin(deg2rad(($lon2 - $lon1) / 2)), 2);
    $d = asin(min(1, sqrt($a + $b * $c)));
    return round(2 * 3960.00 * $d, 4);
}

$lat_1 = "47.117828";
$lon_1 = "-88.545625";
$lat_2 = "47.122223";
$lon_2 = "-88.568781";
$slc_distance = distance_slc($lat_1, $lon_1, $lat_2, $lon_2);
$hav_distance = distance_haversine($lat_1, $lon_1, $lat_2, $lon_2);
var_dump($slc_distance, $hav_distance);