tabla de ajedrez

<?php

function tablaAjedrez($ancho=8, $alto=8)
{
    $tablero = "";
    for ($x=1; $x<=$alto; $x++) {
        for ($y=1; $y<=$ancho; $y++) {
            $color = $x%2 == $y%2 ? "white" : "black";
            $tablero .= "<div class=\"square $color\">$x,$y</div>";
        }
    }
    echo "<div class=\"chessboard\">$tablero</div>";
}

tablaAjedrez(5,5);
?>