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
     {

include/ddc/kernels/splines/spline_evaluator.hpp

@@ -15,57 +15,93 @@
 
 namespace ddc {
 
+/**
+ * @brief A class to evaluate, differentiate or integrate a spline function.
+ *
+ * A class which contains an operator () which can be used to evaluate, differentiate or integrate a spline function.
+ *
+ * @tparam ExecSpace The Kokkos execution space on which the spline evaluation is performed.
+ * @tparam MemorySpace The Kokkos memory space on which the data (spline coefficients and evaluation) is stored.
+ * @tparam BSplines The discrete dimension representing the B-splines.
+ * @tparam EvaluationMesh The discrete dimension on which evaluation points are defined.
+ * @tparam LeftExtrapolationRule The lower extrapolation rule type.
+ * @tparam RightExtrapolationRule The upper extrapolation rule type.
+ * @tparam IDimX A variadic template of all the discrete dimensions forming the full space (EvaluationMesh + batched dimensions).
+ */
 template <
         class ExecSpace,
         class MemorySpace,
-        class BSplinesType,
+        class BSplines,
         class EvaluationMesh,
         class LeftExtrapolationRule,
         class RightExtrapolationRule,
         class... IDimX>
 class SplineEvaluator
 {
 private:
-    // Tags to determine what to evaluate
+    /**
+     * @brief Tag to indicate that the value of the spline should be evaluated.
+     */
     struct eval_type
     {
     };
 
+    /**
+     * @brief Tag to indicate that derivative of the spline should be evaluated.
+     */
     struct eval_deriv_type
     {
     };
 
-    using tag_type = typename BSplinesType::tag_type;
+    using tag_type = typename BSplines::tag_type;
 
 public:
+    /// @brief The type of the Kokkos execution space used by this class.
     using exec_space = ExecSpace;
 
+    /// @brief The type of the Kokkos memory space used by this class.
     using memory_space = MemorySpace;
 
-    using bsplines_type = BSplinesType;
-
-    using left_extrapolation_rule_type = LeftExtrapolationRule;
-    using right_extrapolation_rule_type = RightExtrapolationRule;
-
+    /// @brief The type of the evaluation discrete dimension (discrete dimension of interest) used by this class.
     using evaluation_mesh_type = EvaluationMesh;
 
+    /// @brief The discrete dimension representing the B-splines.
+    using bsplines_type = BSplines;
+
+    /// @brief The type of the domain for the 1D evaluation mesh used by this class.
     using evaluation_domain_type = ddc::DiscreteDomain<evaluation_mesh_type>;
 
+    /// @brief The type of the whole domain representing evaluation points.
     using batched_evaluation_domain_type = ddc::DiscreteDomain<IDimX...>;
 
+    /// @brief The type of the 1D spline domain corresponding to the dimension of interest.
     using spline_domain_type = ddc::DiscreteDomain<bsplines_type>;
 
+    /**
+     * @brief The type of the batch domain (obtained by removing the dimension of interest
+     * from the whole domain).
+     */
     using batch_domain_type =
             typename ddc::detail::convert_type_seq_to_discrete_domain<ddc::type_seq_remove_t<
                     ddc::detail::TypeSeq<IDimX...>,
                     ddc::detail::TypeSeq<evaluation_mesh_type>>>;
 
+    /**
+     * @brief The type of the whole spline domain (cartesian product of 1D spline domain
+     * and batch domain) preserving the order of dimensions.
+     */
     using batched_spline_domain_type =
             typename ddc::detail::convert_type_seq_to_discrete_domain<ddc::type_seq_replace_t<
                     ddc::detail::TypeSeq<IDimX...>,
                     ddc::detail::TypeSeq<evaluation_mesh_type>,
                     ddc::detail::TypeSeq<bsplines_type>>>;
 
+    /// @brief The type of the extrapolation rule at the lower boundary.
+    using left_extrapolation_rule_type = LeftExtrapolationRule;
+
+    /// @brief The type of the extrapolation rule at the upper boundary.
+    using right_extrapolation_rule_type = RightExtrapolationRule;
+
 
 private:
     LeftExtrapolationRule m_left_extrap_rule;
@@ -105,6 +141,14 @@ class SplineEvaluator
                             memory_space>>,
             "RightExtrapolationRule::operator() has to be callable with usual arguments.");
 
+    /**
+     * @brief Build a SplineEvaluator acting on batched_spline_domain.
+     * 
+     * @param left_extrap_rule The extrapolation rule at the lower boundary.
+     * @param right_extrap_rule The extrapolation rule at the upper boundary.
+     *
+     * @see NullExtrapolationRule ConstantExtrapolationRule PeriodicExtrapolationRule
+     */
     explicit SplineEvaluator(
             LeftExtrapolationRule const& left_extrap_rule,
             RightExtrapolationRule const& right_extrap_rule)
@@ -113,26 +157,79 @@ class SplineEvaluator
     {
     }
 
+    /**
+     * @brief Copy-constructs.
+     *
+     * @param x A reference to another SplineEvaluator.
+     */
     SplineEvaluator(SplineEvaluator const& x) = default;
 
+    /**
+     * @brief Move-constructs.
+     *
+     * @param x An rvalue to another SplineEvaluator.
+     */
     SplineEvaluator(SplineEvaluator&& x) = default;
 
+    /// @brief Destructs
     ~SplineEvaluator() = default;
 
+    /**
+     * @brief Copy-assigns.
+     *
+     * @param x A reference to another SplineEvaluator.
+     * @return A reference to this object.
+     */
     SplineEvaluator& operator=(SplineEvaluator const& x) = default;
 
+    /**
+     * @brief Move-assigns.
+     *
+     * @param x An rvalue to another SplineEvaluator.
+     * @return A reference to this object.
+     */
     SplineEvaluator& operator=(SplineEvaluator&& x) = default;
 
+    /**
+     * @brief Get the lower extrapolation rule.
+     *
+     * Extrapolation rules are functors used to define the behavior of the SplineEvaluator out of the domain where the break points of the B-splines are defined.
+     *
+     * @return The lower extrapolation rule. 
+     *
+     * @see NullExtrapolationRule ConstantExtrapolationRule PeriodicExtrapolationRule
+     */
     left_extrapolation_rule_type left_extrapolation_rule() const
     {
         return m_left_extrap_rule;
     }
 
+    /**
+     * @brief Get the upper extrapolation rule.
+     *
+     * Extrapolation rules are functors used to define the behavior of the SplineEvaluator out of the domain where the break points of the B-splines are defined.
+     *
+     * @return The upper extrapolation rule. 
+     *
+     * @see NullExtrapolationRule ConstantExtrapolationRule PeriodicExtrapolationRule
+     */
     right_extrapolation_rule_type right_extrapolation_rule() const
     {
         return m_right_extrap_rule;
     }
 
+    /**
+     * @brief Evaluate 1D spline function (described by its spline coefficients) at a given coordinate.
+     *
+     * The spline coefficients represent a 1D spline function defined on a B-splines (basis splines). They can be obtained via various methods, such as using a SplineBuilder.
+     *
+     * Remark: calling SplineBuilder then SplineEvaluator corresponds to a spline interpolation.
+     *
+     * @param coord_eval The coordinate where the spline is evaluated. Note that only the component along the dimension of interest is used.
+     * @param spline_coef A ChunkSpan storing the 1D spline coefficients.
+     *
+     * @return The value of the spline function at the desired coordinate. 
+     */
     template <class Layout, class... CoordsDims>
     KOKKOS_FUNCTION double operator()(
             ddc::Coordinate<CoordsDims...> const& coord_eval,
@@ -142,6 +239,26 @@ class SplineEvaluator
         return eval(coord_eval, spline_coef);
     }
 
+    /**
+     * @brief Evaluate spline function (described by its spline coefficients) on a mesh.
+     *
+     * The spline coefficients represent a spline function defined on a cartesian product of batch_domain and B-splines
+     * (basis splines). They can be obtained via various methods, such as using a SplineBuilder.
+     *
+     * This is not a multidimensional evaluation. This is a batched 1D evaluation. This means that for each slice of coordinates
+     * identified by a batch_domain_type::discrete_element_type, the evaluation is performed with the 1D set of
+     * spline coefficients identified by the same batch_domain_type::discrete_element_type.
+     *
+     * Remark: calling SplineBuilder then SplineEvaluator corresponds to a spline interpolation.
+     *
+     * @param[out] spline_eval The values of the spline function at the desired coordinates. For practical reasons those are
+     * stored in a ChunkSpan defined on a batched_evaluation_domain_type.
+     * @param[in] coords_eval The coordinates where the spline is evaluated. Those are
+     * stored in a ChunkSpan defined on a batched_evaluation_domain_type. Note that the coordinates of the
+     * points represented by this domain are unused and irrelevant (but the points themselves (DiscreteElement) are used to select
+     * the set of 1D spline coefficients retained to perform the evaluation).
+     * @param[in] spline_coef A ChunkSpan storing the spline coefficients.
+     */
     template <class Layout1, class Layout2, class Layout3, class... CoordsDims>
     void operator()(
             ddc::ChunkSpan<double, batched_evaluation_domain_type, Layout1, memory_space> const
@@ -170,6 +287,17 @@ class SplineEvaluator
                 });
     }
 
+    /**
+     * @brief Differentiate 1D spline function (described by its spline coefficients) at a given coordinate.
+     *
+     * The spline coefficients represent a 1D spline function defined on a B-splines (basis splines). They can be
+     * obtained via various methods, such as using a SplineBuilder.
+     *
+     * @param coord_eval The coordinate where the spline is differentiated. Note that only the component along the dimension of interest is used.
+     * @param spline_coef A ChunkSpan storing the 1D spline coefficients.
+     *
+     * @return The derivative of the spline function at the desired coordinate. 
+     */
     template <class Layout, class... CoordsDims>
     KOKKOS_FUNCTION double deriv(
             ddc::Coordinate<CoordsDims...> const& coord_eval,
@@ -179,6 +307,24 @@ class SplineEvaluator
         return eval_no_bc<eval_deriv_type>(coord_eval, spline_coef);
     }
 
+    /**
+     * @brief Differentiate spline function (described by its spline coefficients) on a mesh.
+     *
+     * The spline coefficients represent a spline function defined on a cartesian product of batch_domain and B-splines
+     * (basis splines). They can be obtained via various methods, such as using a SplineBuilder.
+     *
+     * The derivation is not performed in a multidimensional way (in any sense). This is a batched 1D derivation.
+     * This means that for each slice of coordinates identified by a batch_domain_type::discrete_element_type,
+     * the derivation is performed with the 1D set of spline coefficients identified by the same batch_domain_type::discrete_element_type.
+     *
+     * @param[out] spline_eval The derivatives of the spline function at the desired coordinates. For practical reasons those are
+     * stored in a ChunkSpan defined on a batched_evaluation_domain_type.
+     * @param[in] coords_eval The coordinates where the spline is differentiated. Those are
+     * stored in a ChunkSpan defined on a batched_evaluation_domain_type. Note that the coordinates of the
+     * points represented by this domain are unused and irrelevant (but the points themselves (DiscreteElement) are used to select
+     * the set of 1D spline coefficients retained to perform the evaluation).
+     * @param[in] spline_coef A ChunkSpan storing the spline coefficients.
+     */
     template <class Layout1, class Layout2, class Layout3, class... CoordsDims>
     void deriv(
             ddc::ChunkSpan<double, batched_evaluation_domain_type, Layout1, memory_space> const
@@ -208,6 +354,19 @@ class SplineEvaluator
                 });
     }
 
+    /** @brief Perform batched 1D integrations of a spline function (described by its spline coefficients) along the dimension of interest and store results on a subdomain of batch_domain.
+     *
+     * The spline coefficients represent a spline function defined on a B-splines (basis splines). They can be obtained via the SplineBuilder.
+     *
+     * The integration is not performed in a multidimensional way (in any sense). This is a batched 1D integration.
+     * This means that for each element of integrals, the integration is performed with the 1D set of
+     * spline coefficients identified by the same DiscreteElement.
+     *
+     * @param[out] integrals The integrals of the spline function on the subdomain of batch_domain. For practical reasons those are
+     * stored in a ChunkSpan defined on a batch_domain_type. Note that the coordinates of the
+     * points represented by this domain are unused and irrelevant.
+     * @param[in] spline_coef A ChunkSpan storing the spline coefficients.
+     */
     template <class Layout1, class Layout2>
     void integrate(
             ddc::ChunkSpan<double, batch_domain_type, Layout1, memory_space> const integrals,