sub nonlin {
    my ( $x, $deriv ) = @_;
    my $f = 1 / ( 1 + exp( -$x ) );
    return $f * ( 1 - $f ) if defined $deriv;
    return $f;
}

##</code><code>##

Output After Training:
[
 [ 0.0007225057]
 [0.00048051061]
 [     0.999593]
 [     0.999388]
]