Calculation of IDW for the test set (from "Soil mapping for precision agriculture using support vector machines combined with inverse distance weighting")

[sanan2005]

I have been using Smart-Map plugin for a while. Recently, I tried to use SVM machine learning, study how IDW for the test set can be calculated, and try to calculate that by myself. I ended up with different values of features calculated by IDW. I tried to plot the test set in the map, and the values of IDW in the test set did not follow the local variation of the known values. They are kinda upside down, the location where the attribute should be high, it is low, and vice versa. Could you share the example of calculation of IDW for test set?