ipa: libipa: vector: Add sum() function

Add a function to calculate the sum of a vector. It will be useful for
algorithms.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>

src/ipa/libipa/vector.cpp

@@ -289,6 +289,18 @@ namespace ipa {
  * \return The length of the vector
  */
 
+/**
+ * \fn Vector::sum() const
+ * \brief Calculate the sum of all the vector elements
+ * \tparam R The type of the sum
+ *
+ * The type R of the sum defaults to the type T of the elements, but can be set
+ * explicitly to use a different type in case the type T would risk
+ * overflowing.
+ *
+ * \return The sum of all the vector elements
+ */
+
 /**
  * \fn Vector<T, Rows> operator*(const Matrix<T, Rows, Cols> &m, const Vector<T, Cols> &v)
  * \brief Multiply a matrix by a vector

src/ipa/libipa/vector.h

@@ -10,6 +10,7 @@
 #include <array>
 #include <cmath>
 #include <functional>
+#include <numeric>
 #include <optional>
 #include <ostream>
 
@@ -239,6 +240,12 @@ public:
 		return std::sqrt(length2());
 	}
 
+	template<typename R = T>
+	constexpr R sum() const
+	{
+		return std::accumulate(data_.begin(), data_.end(), R{});
+	}
+
 private:
 	template<class BinaryOp>
 	static constexpr Vector apply(const Vector &lhs, const Vector &rhs, BinaryOp op)