grand_canonical

Grand canonical weight

context	$\Xi(\beta,\mu)$ … grand canonical partition function
definiendum	$w: \mathbb N \to {\mathbb R\times\mathbb R} \to \mathbb R$
definiendum	$w_N(\beta,\mu):=\frac{1}{\Xi(\beta,\mu)}\ z(\beta,\mu)^N\cdot Z_N(\beta)$