A FORTRAN PROGRAM FOR 3-DIMENSIONAL COKRIGING WITH CASE DEMONSTRATION

This paper presents a three-dimensional (3-D) cokriging program, which generally is suitable for any anisotropic multivariate system in which variables are correlated spatially. The code was written in standard FORTRAN 77. The program is executed with a control file which defines all parameters necessary to run the program. Options for variogram/cross variogram models are spherical, Gaussian, exponential, DeWijsian, and linear. The program provides alternatives for point/block cokriging and cross validation. A 3-D search strategy is adopted on a "main variables" basis. In addition, the program employs a heuristic criterion to eliminate instabilities in solving the cokriging equation system and allows automatic adjustment for under-sampled cases. Finally, the program is demonstrated by a case study based on a real data set.