This code is an implementation of the CTMRG algorithm introduced in the articles:
Corner Transfer Matrix Renormalization Group Method J. Phys. Soc. Jpn. 65, pp. 891-894 (1996) http://arxiv.org/abs/cond-mat/9507087v5
Corner Transfer Matrix Algorithm for Classical Renormalization Group J. Phys. Soc. Jpn. 66, pp. 3040-3047 (1997) http://arxiv.org/abs/cond-mat/9705072
For linear algebra (matrix diagonalization in particular), Eigen library (3.2.7) is called.
Compilation under Mac:
g++ -m64 -O3 -I/.../Eigen main.cpp -o main.x