'plot' method for class "Sncf".
# S3 method for Sncf
plot(x, ylim = c(-1, 1), add = FALSE, ...)an object of class "Sncf", usually, as a result of a call to Sncf (or Sncf.srf).
limits for the y-axis (default: -1, 1).
If TRUE the plot is added on to the previous graph.
other arguments
A plot of the nonparametric spatial covariance function (with CI's if bootstraps are available)