hamiltonian_ising: Hamiltonian of Generalized Ising Model
In XiaoqiLu/ziclust: What the Package Does (One Line, Title Case)

Description Usage Arguments Details Value Examples

hamiltonian_ising is used to compute the energy of given configuration in a generalized Ising model.

1	hamiltonian_ising(u, h, J = NULL)

`u`	a binary (-1, 1-valued) vector or matrix. If `u` is a matrix, each row is taken as an input vector.
`h`	a vector giving the external field.
`J`	a symmetric matrix with zero diagonals giving the interaction. If `J` is `NULL`, the model degenerates to the case of independent binary.

The generalized Ising model (also known as quadratic exponential binary distribution) is generalizing the adjacent coupling of Ising model to two-way interactions. The probability mass function of generalized Ising model is

P(u \vert h, J) = \frac{1}{Z(h, J)} e^{- H(u; h, J)},

where H(u; h, J) = - h^T u - \frac{1}{2} u^T J u is the Hamiltonian.

a vector giving the energy of configuration u

hamiltonian_ising(
  u = c(+1, +1),
  h = c(0, 0),
  J = matrix(c(0, -1, -1, 0), 2, 2)
)

hamiltonian_ising(
  u = matrix(c(-1, +1, +1, -1), 2, 2, byrow = TRUE),
  h = c(2, 3),
  J = matrix(0, 2, 2)
)