for $q=6$ and $L=256$.

![(Color online) Finite size scaling of the susceptibility for $q=2$. (main plot) $\chi$ as a function of temperature for different system linear sizes. Averages were taken over several samples ranging from $300$ for small system sizes down to $50$ and $15$ for $L=1024$ and $L=2048$, respectively. We have used equally equilibration and measurement times of $2\times10^5 \mathit{MCS}$, measuring quantities each $10 \mathit{MCS}$, thus totalizing averages over $6\times 10^6$ to $3\times 10^5$ as we increase the system size. (upper inset) Maximum value of the susceptibility peak $\chi_{max}$ [*vs.*]{} $L$. Error bars, estimated from the uncertainty when evaluating the maximum, are smaller than the symbol size. (lower inset) Pseudo critical temperature $T^*(L)$ [*vs.*]{} $1/L$. Error bars, estimated from the uncertainty when locating the position of the maximum, are shown only when larger than the symbol size. []{data-label="q2chi"}](fig4.eps)

In addition, we test our code for the $q=2$ (Ising) case. Fig.\[q2chi\] shows the susceptibility of the order parameter calculated as $$\chi  = \frac{N}{T} \left[\left<m^2\right> - \left<m\right>^2\right]$$

The extrapolated value of the pseudo critical temperature $T^*(L)$ (defined as the location of the susceptibility maximum) for $L\to\infty$, $1.1345\pm0.0001$, agrees with the exact value[^3] $T_c(q=2)=1.1345926...$ within an accuracy of the $0.009\%$. Even more, 