use PDL;
use strict;
use warnings;

use constant X_NPOINTS => 11;
use constant Y_NPOINTS => 11;

my $proto = zeroes( X_NPOINTS, Y_NPOINTS );
my $x = $proto->xvals;
my $y = $proto->yvals;

my $z = sqrt( 1/(0.5 + 0.02*$x**2)*cos($x)
            + 1/(0.5 + 0.02*$y**2)*cos($y) );