Builds a spatial covariance matrix using an RBF kernel with a nugget
term for numerical stability.
Usage
space_kernel(coordinates, length_scale, nugget = 1e-09)
Arguments
- coordinates
A data frame with columns `lon` and `lat` in degrees.
- length_scale
A positive numeric scalar for the spatial length scale.
- nugget
A non-negative numeric scalar added to the diagonal for
numerical stability.
Value
A positive-definite matrix representing spatial covariance.