Polynomial algorithm for exact calculation of partition function for binary spin model on planar graphs

In this paper we propose and realize (the code is publicly available at https://github.com/Thrawn1985/2D-Partition-Function) an algorithm for exact calculation of partition function for planar graph models with binary spins. The complexity of the algorithm is O(N^2). Test experiments shows good agreement with Onsagers analytical solution for two-dimensional Ising model of infinite size.