This function calculates the normalizing constant of a Mallows distribution under the Kendall distance
psi(theta, J, R, log = FALSE)A numeric entry specifying the Mallows scale parameter.
A numeric entry or vector of positive integers indicating total number of objects each judge has access to.
If length(J)>1, R must be of same length or a single value.
A numeric entry or vector of positive integers indicating the length of the ranking provided by each judge.
If length(R)>1, J must be of same length or a single value.
A boolean indicating if log(psi) should be returned.
A numeric value or vector representing normalizing constant of a Mallows distribution.