walk_step: Performs a step of the Markov Chain Monte Carlo method
Description
Modifies the matrix while keeping the column and row sums constant, as well as
leaving the positions strictly preceding (k,l) in lexicographical order invariant.
Usage
walk_step(M, k, l)
Value
boolean indicating whether the step left the matrix invariant
Arguments
M
matrix
k, l
Coordinates of the first element that is not invariant