SplineEvaluator doc

include/ddc/kernels/splines/null_extrapolation_rule.hpp

@@ -8,8 +8,16 @@
 
 namespace ddc {
 
+/**
+ * @brief A functor describing a null extrapolation boundary value for 1D spline evaluator.
+ */
 struct NullExtrapolationRule
 {
+    /**
+     * @brief Evaluates the spline at a coordinate outside of the domain.
+     *
+     * @return A double with the value of the function outside the domain (here, 0.).
+     */
     template <class CoordType, class ChunkSpan>
     KOKKOS_FUNCTION double operator()(CoordType, ChunkSpan) const
     {