| ddpen_hi | penalize large values of parameter: penalty, 1st deriative, 2nd derivative | 
| ddpen_lo | penalize small values of parameter: penalty, 1st deriative, 2nd derivative | 
| ddpen_loglo | penalize small values of log parameter: penalty, 1st deriative, 2nd derivative | 
| dpen_hi | penalize large values of parameter: penalty, 1st deriative, 2nd derivative | 
| dpen_lo | penalize small values of parameter: penalty, 1st deriative, 2nd derivative | 
| dpen_loglo | penalize small values of log parameter: penalty, 1st deriative, 2nd derivative | 
| d_exponential_anisotropic2D | Geometrically anisotropic exponential covariance function (two dimensions) | 
| d_exponential_anisotropic3D | Geometrically anisotropic exponential covariance function (three dimensions) | 
| d_exponential_anisotropic3D_alt | Geometrically anisotropic exponential covariance function (three dimensions, alternate parameterization) | 
| d_exponential_isotropic | Isotropic exponential covariance function | 
| d_exponential_nonstat_var | Isotropic exponential covariance function, nonstationary variances | 
| d_exponential_scaledim | Exponential covariance function, different range parameter for each dimension | 
| d_exponential_spacetime | Spatial-Temporal exponential covariance function | 
| d_exponential_sphere | Isotropic exponential covariance function on sphere | 
| d_exponential_spheretime | Exponential covariance function on sphere x time | 
| d_exponential_spheretime_warp | Deformed exponential covariance function on sphere | 
| d_exponential_sphere_warp | Deformed exponential covariance function on sphere | 
| d_matern15_isotropic | Isotropic exponential covariance function | 
| d_matern15_scaledim | Matern covariance function, smoothess = 1.5, different range parameter for each dimension | 
| d_matern25_isotropic | Isotropic exponential covariance function | 
| d_matern25_scaledim | Matern covariance function, smoothess = 2.5, different range parameter for each dimension | 
| d_matern35_isotropic | Isotropic Matern covariance function, smoothness = 3.5 | 
| d_matern35_scaledim | Matern covariance function, smoothess = 3.5, different range parameter for each dimension | 
| d_matern45_isotropic | Isotropic Matern covariance function, smoothness = 3.5 | 
| d_matern45_scaledim | Matern covariance function, smoothess = 3.5, different range parameter for each dimension | 
| d_matern_anisotropic2D | Geometrically anisotropic Matern covariance function (two dimensions) | 
| d_matern_anisotropic3D | Geometrically anisotropic Matern covariance function (three dimensions) | 
| d_matern_anisotropic3D_alt | Geometrically anisotropic Matern covariance function (three dimensions) | 
| d_matern_categorical | Isotropic Matern covariance function with random effects for categories | 
| d_matern_isotropic | Isotropic Matern covariance function | 
| d_matern_nonstat_var | Isotropic Matern covariance function, nonstationary variances | 
| d_matern_scaledim | Matern covariance function, different range parameter for each dimension | 
| d_matern_spacetime | Spatial-Temporal Matern covariance function | 
| d_matern_spacetime_categorical | Space-Time Matern covariance function with random effects for categories | 
| d_matern_spacetime_categorical_local | Space-Time Matern covariance function with local random effects for categories | 
| d_matern_sphere | Isotropic Matern covariance function on sphere | 
| d_matern_spheretime | Matern covariance function on sphere x time | 
| d_matern_spheretime_warp | Deformed Matern covariance function on sphere | 
| d_matern_sphere_warp | Deformed Matern covariance function on sphere | 
| matern15_isotropic | Isotropic Matern covariance function, smoothness = 1.5 | 
| matern15_scaledim | Matern covariance function, smoothess = 1.5, different range parameter for each dimension | 
| matern25_isotropic | Isotropic Matern covariance function, smoothness = 2.5 | 
| matern25_scaledim | Matern covariance function, smoothess = 2.5, different range parameter for each dimension | 
| matern35_isotropic | Isotropic Matern covariance function, smoothness = 3.5 | 
| matern35_scaledim | Matern covariance function, smoothess = 3.5, different range parameter for each dimension | 
| matern45_isotropic | Isotropic Matern covariance function, smoothness = 4.5 | 
| matern45_scaledim | Matern covariance function, smoothess = 3.5, different range parameter for each dimension | 
| matern_anisotropic2D | Geometrically anisotropic Matern covariance function (two dimensions) | 
| matern_anisotropic3D | Geometrically anisotropic Matern covariance function (three dimensions) | 
| matern_anisotropic3D_alt | Geometrically anisotropic Matern covariance function (three dimensions, alternate parameterization) | 
| matern_categorical | Isotropic Matern covariance function with random effects for categories | 
| matern_isotropic | Isotropic Matern covariance function | 
| matern_nonstat_var | Isotropic Matern covariance function, nonstationary variances | 
| matern_scaledim | Matern covariance function, different range parameter for each dimension | 
| matern_spacetime | Spatial-Temporal Matern covariance function | 
| matern_spacetime_categorical | Space-Time Matern covariance function with random effects for categories | 
| matern_spacetime_categorical_local | Space-Time Matern covariance function with local random effects for categories | 
| matern_sphere | Isotropic Matern covariance function on sphere | 
| matern_spheretime | Matern covariance function on sphere x time | 
| matern_spheretime_warp | Deformed Matern covariance function on sphere | 
| matern_sphere_warp | Deformed Matern covariance function on sphere |