Get a lat/long radius from passed latitude and longitude

get-radius.php

<?php

/**
 * Calculate the longitude and latitude or a radius around a location
 *
 * Returns an array with the following keys: `LatitudeMax`, `LongitudeMax`, `LatitudeMin`, `LongitudeMin`, to produce a radius search
 *
 * @param  string|float  $longitude The longitude to calculate from
 * @param  string|float  $latitude  The latitude to calculate from
 * @param  integer $miles     Number of miles for the radius
 *
 * @return array             Array with longitude-max
 */
function get_radius( $longitude, $latitude, $miles = 5 ) {

	/**
	 * Latitude: degree is approximately 69.172 miles, and a minute of latitude is approximately 1.15 miles
	 * Longitude: degree ~54.6 miles, minute ~0.91 miles
	 * @see https://www.usgs.gov/faqs/how-much-distance-does-a-degree-minute-and-second-cover-your-maps
	 */
	$degrees = $miles / 69.172 / 100;
	$minutes = $miles / 1.15 / 100;

	$settings = array(
		'LatitudeMax' => floatval( $latitude) + $degrees,
		'LatitudeMin' => floatval( $latitude ) - $degrees,
		'LongitudeMax' => floatval( $longitude ) + $minutes,
 		'LongitudeMin' => floatval( $longitude ) - $minutes,
	);

	return $settings;
}