gistfile1.aw

function easterDay($y) {
  // Se http://aa.usno.navy.mil/faq/docs/easter.html
  $c = floor($y / 100);
  $n = $y - 19 * floor( $y / 19 );
  $k = floor(( $c - 17 ) / 25);
  $i = $c - floor($c / 4) - floor(( $c - $k ) / 3) + 19 * $n + 15;
  $i = $i - 30 * floor( $i / 30 );
  $i = $i - floor( $i / 28 ) * ( 1 - floor( $i / 28 ) * floor( 29 / ( $i + 1 ) )
                * floor( ( 21 - $n ) / 11 ) );
  $j = $y + floor($y / 4) + $i + 2 - $c + floor($c / 4);
  $j = $j - 7 * floor( $j / 7 );
  $l = $i - $j;
  $m = 3 + floor(( $l + 40 ) / 44); // month
  $d = $l + 28 - 31 * floor( $m / 4 ); // day

  return ($m == 3 ? $d : $d+31);
}