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53 lines
1.6 KiB
53 lines
1.6 KiB
#ifndef MEDUSA_BITS_APPROXIMATIONS_POLYHARMONIC_HPP_
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#define MEDUSA_BITS_APPROXIMATIONS_POLYHARMONIC_HPP_
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/**
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* @file
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* Implementation of Polyharmonic RBF.
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*/
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#include "Polyharmonic_fwd.hpp"
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#include <medusa/bits/utils/numutils.hpp>
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namespace mm {
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template <typename scal_t, int k>
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Polyharmonic<scal_t, k>::Polyharmonic() : order_(k) {
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assert_msg(order_ > 0, "Order must be supplied if compile type order is -1.");
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}
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template <typename scal_t, int k>
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Polyharmonic<scal_t, k>::Polyharmonic(int order) : order_((k < 0) ? order : k) {
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assert_msg(order % 2 == 1, "Order must be odd, got %d.", order);
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}
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template <typename scal_t, int k>
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scal_t Polyharmonic<scal_t, k>::operator()(scal_t r2, int derivative) const {
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assert_msg(derivative >= 0, "Derivative of negative order %d requested.", derivative);
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if (r2 < 1e-15) {
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return 0;
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}
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scalar_t r = std::sqrt(ipowneg(r2, order_ - 2*derivative));
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while (--derivative >= 0) {
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r *= (order_/2.0 - derivative);
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}
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return r;
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}
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/// @cond
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template <typename scal_t, int k>
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template <int dimension>
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scal_t Polyharmonic<scal_t, k>::operator()(scal_t r2, Lap<dimension>) const {
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assert_msg(order_ > 2, "Order must be > 2 to compute the Laplacian, got %d.", k);
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return (dimension + order_ - 2)*order_*ipow(std::sqrt(r2), order_ - 2);
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}
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/// @endcond
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/// Output basic information about given Gaussian RBF.
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template <class S, int K>
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std::ostream& operator<<(std::ostream& os, const Polyharmonic<S, K>& b) {
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return os << "Polyharmonic RBF of order " << b.order_ << '.';
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}
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} // namespace mm
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#endif // MEDUSA_BITS_APPROXIMATIONS_POLYHARMONIC_HPP_
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