corr_nn                 Find ordered nearest neighbors based on
                        correlation, assuming the absolute value of the
                        correlation is monotonically decreasing with
                        distance. Returns an n X (m + 1) matrix, each
                        row indicating the m + 1 nearest neighbors
                        including itself.
nntmvn                  nntmvn
rptmvn                  Draw one sample of the underlying GP responses
                        for a partially censored Gaussian process using
                        sequential nearest neighbor (SNN) method
rtmvn                   Draw one sample from a truncated multivariate
                        normal (TMVN) distribution using sequential
                        nearest neighbor (SNN) method
