sub mat_hash {
    my %cells;

    $cells{$_->[0]}{$_->[1]} = undef for @points;
    my $ncells = 0;
    $ncells += keys %{$cells{$_}} for keys %cells;
    $ncells == $npoints or die;
    exists $cells{$_->[0]}{$_->[1]} or die for @points;
    exists $cells{'notfound'} and die;
    exists $cells{'notfound2'} and die;
    exists $cells{'notfound3'} and die;
    return \%cells;
}

sub mat_look {
    my $cells = shift;
    exists $cells->{$_->[0]}{$_->[1]} or die for @points;
    exists $cells->{'notfound'} and die;
    exists $cells->{'notfound2'} and die;
    exists $cells->{'notfound3'} and die;
}

my $str_ref = str_hash();
my $big_ref = big_hash();
my $pak_ref = pak_hash();
my $mat_ref = mat_hash();

timethese 200000, {
   Str => sub { str_look($str_ref) },
   Big => sub { big_look($big_ref) },
   Pak => sub { pak_look($pak_ref) },
   Mat => sub { mat_look($mat_ref) },
};