1 files changed, 36 insertions, 0 deletions
diff --git a/modules/core/c++/macroscopic.hpp b/modules/core/c++/macroscopic.hpp
new file mode 100644
index 0000000..19ab3e9
--- /dev/null
+++ b/modules/core/c++/macroscopic.hpp
@@ -0,0 +1,36 @@
+#pragma once
+
+#include "descriptor.hpp"
+
+namespace kel {
+namespace lbm {
+/**
+ * Calculate the macroscopic variables rho and u in Lattice Units.
+ */
+template<typename T, typename Desc>
+void compute_rho_u (
+		const saw::data<sch::FixedArray<T,Desc::Q>>& dfs,
+		saw::ref<saw::data<sch::Scalar<T>>> rho,
+		saw::ref<saw::data<sch::Vector<T,Desc::D>>> vel
+	)
+{
+	using dfi = df_info<T, Desc>;
+
+	rho().at({}).set(0);
+	for(uint64_t i = 0; i < Desc::D; ++i){
+		vel().at({{i}}).set(0);
+	}
+
+	for(size_t j = 0; j < Desc::Q; ++j){
+		rho().at({}) = rho().at({}) + dfs.at({j});
+		for(size_t i = 0; i < Desc::D; ++i){
+			vel().at({{i}}) = vel().at({{i}}) + saw::data<T>{static_cast<typename saw::native_data_type<T>::type>(dfi::directions[j][i])} * dfs.at({j});
+		}
+	}
+
+	for(size_t i = 0; i < Desc::D; ++i){
+		vel().at({{i}}) = vel().at({{i}}) / rho().at({});
+	}
+}
+}
+}