SPECSIM: a program for simulating random fields by an improved spectral approach

Abstract We present the program SPECSIM, coded in ANSI standard FORTRAN 77, which will be used to generate realizations of an isotropic Gaussian second-order stationary function in 1D, 2D, or 3D. The Fourier integral spectrum method has been applied. Statistics of the simulations will be presented as will the calculation time required for the generation of the different realizations. The program can be included within the nonconditional simulation category, as well as within the scope of geostatistic conditional simulation.