These relations are extremely useful, and even allow us to extract exponents
and . But only if we are at ``large enough'' **L**.
If is very large (but not infinite), may get incorrect
``pseudo-critical'' exponents.

This is often the case at a ``weakly'' first order transition (very small latent heat). So it is often very difficult to distinguish between a first and second order phase transition, or even to say for sure if there is a phase transition at all --- is , or just ? May need extremely large system sizes to get correct results.

In general, don't know the form of the finite size scaling, so try to fit
data to a * scaling function*, or go to large enough systems so
that results constant or can do a simple linear extrapolation.

Paul Coddington, Northeast Parallel Architectures Center at Syracuse University, paulc@npac.syr.edu