Its Math Processsing Error , Everywhere!

http://graph-tool.skewed.de/static/doc/generation.html

Examples
This is a degree sampler which uses rejection sampling to sample from the distribution [Math Processing Error], up to a maximum.
>>> def sample_k(max):
... accept = False
... while not accept:
... k = randint(1,max+1)
... accept = random() < 1.0/k
... return k
...
The following generates a random undirected graph with degree distribution [Math Processing Error] (with k_max=40) and an assortativedegree correlation of the form:
[Math Processing Error]
>>> g = gt.random_graph(1000, lambda: sample_k(40), model="probabilistic",
... vertex_corr=lambda i, k: 1.0 / (1 + abs(i - k)), directed=False,
... n_iter=100)
>>> gt.scalar_assortativity(g, "out")
(0.6321636468713748, 0.01082292099309249)
The following samples an in,out-degree pair from the joint distribution:
[Math Processing Error]
with [Math Processing Error] and [Math Processing Error].