The theta parameters in the function call of covariance functions should be defined more precisely. In the details of some covariance functions the parametrization is defined as (range, sill, [smoothness], nugget). It should be "partial sill" instead of sill. Furthermore, the default values are set to be (1, , 0), which does not coincide with the parametrization stated before, i.e. one default value is missing.