<?php $a=4;$b=3;$c=-1;$d=$e=0;$f=($b*$a);function calc($g,$h,$j,$k){for($l=$g;$l<$h;++$l){$k=$k+$j;echo' '.$k;}return($k);}while($f>0){if($d<$a){$c=calc($d,$a,1,$c);$f=$f-($a-$d);++$e;if($e<$b){$c=calc($e,$b,$a,$c);$f=$f-($b-$e);++$d;if($d<$a){$c=calc($d,$a,-1,$c);$f=$f-($a-$d);++$e;if($e<$b){$j=0-$a;$c=calc($e,$b,$j,$c);$f=$f-($b-$e);}}}}++$d;}?>