#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

# Referenz
{
    my %vars;
    my $mode = 1;
    my $curr_grad = $vars{gradient}->{$mode};

    # ...tu was...
    # $vars{gradient}->{1} = [ [1, 1, 1], [1, 2, 3] ];
    @$curr_grad = ( [1, 1, 1], [1, 2, 3] );

    print $curr_grad->[1]->[1]++, "\n";
    print $vars{gradient}->{$mode}->[1]->[1], "\n";
}