STK_RBF_SPHERICAL computes the spherical correlation function CALL: K = stk_rbf_spherical (H) computes the value of the spherical correlation function at distance H: / | 1 - 3/2 |h| + 1/2 |h|^3 if |h| < 1, K = | | 0 otherwise. \ CALL: K = stk_rbf_spherical (H, DIFF) computes the derivative of the spherical correlation function with respect the H if DIFF is equal to 1, and simply returns the value of the exponential correlation function if DIFF <= 0 (in which case it is equivalent to K = stk_rbf_spherical (H)). ADMISSIBILITY The spherical correlation is a valid correlation function in dimension d <= 3.
Package: stk