Simulating GRFs

Example:

sigma2 <- 1
phi <- 0.2
sim2 <- grf(
  n = 1024, 
  grid = "reg", 
  cov.model = "matern", 
  cov.pars = c(sigma2, phi)
)

## grf: generating grid  32  *  32  with  1024  points
## grf: process with  1  covariance structure(s)
## grf: nugget effect is: tausq= 0 
## grf: covariance model 1 is: exponential(sigmasq=1, phi=0.2)
## grf: decomposition algorithm used is:  cholesky 
## grf: End of simulation procedure. Number of realizations: 1