perldl> $a = zeroes 3,1000;

perldl> $b = zeroes 1000,3;

perldl> help vars
PDL variables in package main::

Name         Type   Dimension       Flow  State          Mem
----------------------------------------------------------------
$a           Double D [3,1000]             P            0.02Mb
$b           Double D [1000,3]             P            0.02Mb