# math¶

Functions

 `entropy`(p[, n]) Calculate the entropy of a distribution. `gcd`(a, b) Computes the greatest common divisor (GCD) of two numbers. Return the greatest common divisor of all of entries in a `lcm`(a, b) Returns the least common multiple (LCM) of two positive numbers. transform an linear operator with a matvec method into a dense numpy array. Given a permutation p of numbers, returns its sign. `qr_li`(A[, cutoff]) QR decomposition with cutoff to discard nearly linear dependent columns in Q. `rq_li`(A[, cutoff]) RQ decomposition with cutoff to discard nearly linear dependent columns in Q. `speigs`(A, k, *args, **kwargs) Wrapper around `scipy.sparse.linalg.eigs()`, lifting the restriction `k < rank(A)-1`. `speigsh`(A, k, *args, **kwargs) Wrapper around `scipy.sparse.linalg.eigsh()`, lifting the restriction `k < rank(A)-1`.

Module description

Different math functions needed at some point in the library.

tenpy.tools.math.LeviCivita3 = array([[[ 0,  0,  0],         [ 0,  0,  1],         [ 0, -1,  0]],         [[ 0,  0, -1],         [ 0,  0,  0],         [ 1,  0,  0]],         [[ 0,  1,  0],         [-1,  0,  0],         [ 0,  0,  0]]])

Levi-Civita Symbol of int type