Spatial Spectral Code

As indicated in the above paper, the following R code can implement the FFT spectral Matern functions. The authors make no claim as to the accuracy of this code and do not claim that it is convenient for general use. The program "tst_dfft2d.R" is a simple test program that illustrates how to use the program "dfft2d.R" and "maternspec2d.R". For details, see the paper.