iksim: A fast algorithm for indicator kriging and simulation in the presence of inequality constraints, hard and soft data

iksim is a fast program for indicator kriging and simulation of continuous or categorical variables in the presence of inequality constraints, hard an d soft data. The speed advantage of iksim program results from the FFT spec tral simulation of the non-conditional p-field. To maintain the full speed of median IK in the presence of missing indicator values corresponding to c onstraint intervals or soft data, the missing values can be reconstructed u sing the marginal z-distribution. The algorithm, program structure, data fi le formats, parameter file, and some Validation checks are presented. (C) 2 000 Elsevier Science Ltd. All rights reserved.