knn.dist <- function(X, k)

{X.d <- as.matrix(dist(X))
n <- nrow(X)
knn.d <- apply(X.d, 2, sort)[k+1,]
m<- 2*max(X.d)
X.knn <- matrix(m, n, n)
diag(X.knn) <- 0
for (i in 1:(n-1)) for (j in (i+1):n)
	if (X.d[i,j] <= knn.d[i] | X.d[i,j] <= knn.d[j])
		{X.knn[i,j] <- (knn.d[i]+knn.d[j])/2
		X.knn[j,i] <- X.knn[i,j]}
return(as.dist(X.knn))}