- sqrt: documentation ( source)
<?php
$d = distance([2,4], [26,9]);
echo 'distance is : ' .$d;
function distance( $p1=array(), $p2=array())
{
$x1 = $p1[0];
$x2 = $p2[0];
$y1 = $p1[1];
$y2 = $p2[1];
echo "y1 is : $y1\n";
echo "y2 is : $y2\n";
echo "x1 is : $x1\n";
echo "x2 is : $x2\n";
$p1 = ($x1 - $x2);
$p2 = ($y1 - $y2);
$distance = sqrt(( $p1 + $p2 **2));
/**
$points = [$p1, $p2];
$distance = array_sum($points);
$distance = sqrt(($x1 - $x2) + ($y1 - $y2))**2;
*/
//$distance = hypot($p1, $p2);
return $distance;
}