dmnorm_gp2Scale (and rmnorm_gp2Scale) calculate the usual Gaussian
likelihood for a fixed set of parameters (but with sparse matrices). Finally,
the distributions must be registered within nimble.
rmnorm_gp2Scale(n, mean, Cov, N, Nnz)Not applicable.
Number of realizations to generate
Vector of mean values
Matrix of size N x N; sparse kernel
Number of measurements in x
Number of measurements in x