A method for determining a property of fluids in formations surrounding an earth borehole includes the following steps: producing, from measurements on a multiplicity of fluid samples, a database of stored fluid property training values related to stored fluid measurement training values; deriving, from the database, radial basis function parameters; deriving formation fluid measurement values; and determining, using radial basis function interpolation, the property of formation fluids from values in the database, the parameters, and the derived formation fluid measurement values.