x

y

$\epsilon \left(x,y\right)$

0

0

$\epsilon \left(0,0\right)$

0.1a

$0.1a\tau$

$\epsilon \left(0.1a,0.1a\tau \right)$

1

$\tau$

$\epsilon \left(1,\tau \right)$

a

$a\tau$

$\epsilon \left(a,a\tau \right)$

2a

$2a\tau$

$\epsilon \left(2a,2a\tau \right)$

for a general point, $x_0$

$y_0=\tau x_0$

$\epsilon \left(x_0,\tau x_0\right)$