install.packages("pracma")

library(pracma)

n <- 36

x <- c(1, 1, -1, -1, runif(n-4, -1, 1)) # add four vertices

y <- c(1, -1, 1, -1, runif(n-4, -1, 1))

u <- cbind(x, y)

v <- numeric(n)

for (i in 1:n) v[i] <- f(c(x[i], y[i]))

kriging(u, v, c(0, 0))                    #=>  0.006177183

kriging(u, v, c(0, 0), type = "simple")     #=>  0.006229557