Add min/max/sum functions to SmallArray

src/utils/SmallArray.hpp

@@ -6,6 +6,7 @@
 #include <utils/PugsAssert.hpp>
 #include <utils/PugsMacros.hpp>
 #include <utils/PugsUtils.hpp>
+#include <utils/Types.hpp>
 
 #include <algorithm>
 
@@ -148,4 +149,60 @@ convert_to_small_array(const Container& given_container)
   return array;
 }
 
+template <typename DataType>
+[[nodiscard]] std::remove_const_t<DataType>
+min(const SmallArray<DataType>& array)
+{
+  using data_type  = std::remove_const_t<DataType>;
+  using index_type = typename SmallArray<DataType>::index_type;
+
+  data_type min_value = std::numeric_limits<data_type>::max();
+  for (index_type i = 0; i < array.size(); ++i) {
+    if (array[i] < min_value) {
+      min_value = array[i];
+    }
+  }
+  return min_value;
+}
+
+template <typename DataType>
+[[nodiscard]] std::remove_const_t<DataType>
+max(const SmallArray<DataType>& array)
+{
+  using data_type  = std::remove_const_t<DataType>;
+  using index_type = typename SmallArray<DataType>::index_type;
+
+  data_type max_value = -std::numeric_limits<data_type>::max();
+  for (index_type i = 0; i < array.size(); ++i) {
+    if (array[i] > max_value) {
+      max_value = array[i];
+    }
+  }
+  return max_value;
+}
+
+template <typename DataType>
+[[nodiscard]] std::remove_const_t<DataType>
+sum(const SmallArray<DataType>& array)
+{
+  using data_type  = std::remove_const_t<DataType>;
+  using index_type = typename SmallArray<DataType>::index_type;
+
+  data_type sum_value = [] {
+    if constexpr (std::is_arithmetic_v<DataType>) {
+      return 0;
+    } else if constexpr (is_tiny_vector_v<DataType> or is_tiny_matrix_v<DataType>) {
+      return zero;
+    } else {
+      static_assert(std::is_arithmetic_v<DataType>, "invalid data type");
+    }
+  }();
+
+  for (index_type i = 0; i < array.size(); ++i) {
+    sum_value += array[i];
+  }
+
+  return sum_value;
+}
+
 #endif   // SMALL_ARRAY_HPP

tests/test_SmallArray.cpp

 #include <catch2/catch_test_macros.hpp>
 #include <catch2/matchers/catch_matchers_all.hpp>
 
+#include <algebra/TinyMatrix.hpp>
+#include <algebra/TinyVector.hpp>
 #include <utils/PugsAssert.hpp>
 #include <utils/SmallArray.hpp>
 #include <utils/Types.hpp>
@@ -281,5 +283,71 @@ TEST_CASE("SmallArray", "[utils]")
       REQUIRE(array[i] == std::numeric_limits<int>::max() / 2);
     }
   }
+
+  SECTION("checking for SmallArray reductions")
+  {
+    SmallArray<int> a(10);
+    a[0] = 13;
+    a[1] = 1;
+    a[2] = 8;
+    a[3] = -3;
+    a[4] = 23;
+    a[5] = -1;
+    a[6] = 13;
+    a[7] = 0;
+    a[8] = 12;
+    a[9] = 9;
+
+    SECTION("Min")
+    {
+      REQUIRE(min(a) == -3);
+    }
+
+    SECTION("Max")
+    {
+      REQUIRE(max(a) == 23);
+    }
+
+    SECTION("Sum")
+    {
+      REQUIRE((sum(a) == 75));
+    }
+
+    SECTION("TinyVector Sum")
+    {
+      using N2 = TinyVector<2, int>;
+      SmallArray<N2> b(10);
+      b[0] = {13, 2};
+      b[1] = {1, 3};
+      b[2] = {8, -2};
+      b[3] = {-3, 2};
+      b[4] = {23, 4};
+      b[5] = {-1, -3};
+      b[6] = {13, 17};
+      b[7] = {0, 9};
+      b[8] = {12, 13};
+      b[9] = {9, -17};
+
+      REQUIRE((sum(b) == N2{75, 28}));
+    }
+
+    SECTION("TinyMatrix Sum")
+    {
+      using N22 = TinyMatrix<2, 2, int>;
+      SmallArray<N22> b(10);
+      b[0] = {13, 2, 0, 1};
+      b[1] = {1, 3, 6, 3};
+      b[2] = {8, -2, -1, 21};
+      b[3] = {-3, 2, 5, 12};
+      b[4] = {23, 4, 7, 1};
+      b[5] = {-1, -3, 33, 11};
+      b[6] = {13, 17, 12, 13};
+      b[7] = {0, 9, 1, 14};
+      b[8] = {12, 13, -3, -71};
+      b[9] = {9, -17, 0, 16};
+
+      REQUIRE((sum(b) == N22{75, 28, 60, 21}));
+    }
+  }
 #endif   // NDEBUG
 }