Refactors the underlying data type to optimize performance

Matrix.cpp

@@ -24,19 +24,18 @@ Matrix<rows, columns>::Matrix(Args... args) {
                                static_cast<uint16_t>(columns)};
 
   std::initializer_list<float> initList{static_cast<float>(args)...};
-  std::array<float, arraySize> data{};
   // choose whichever buffer size is smaller for the copy length
   uint32_t minSize =
       std::min(arraySize, static_cast<uint16_t>(initList.size()));
-  memcpy(data.begin(), initList.begin(), minSize * sizeof(float));
-  this->setMatrixToArray(data);
+  memcpy(this->matrix.begin(), initList.begin(), minSize * sizeof(float));
 }
 
 template <uint8_t rows, uint8_t columns>
 Matrix<rows, columns>::Matrix(const Matrix<rows, columns> &other) {
   for (uint8_t row_idx{0}; row_idx < rows; row_idx++) {
     for (uint8_t column_idx{0}; column_idx < columns; column_idx++) {
-      this->matrix[row_idx][column_idx] = other.Get(row_idx, column_idx);
+      this->matrix[row_idx * columns + column_idx] =
+          other.Get(row_idx, column_idx);
     }
   }
 }
@@ -50,9 +49,9 @@ void Matrix<rows, columns>::setMatrixToArray(
           static_cast<uint16_t>(row_idx) * static_cast<uint16_t>(columns) +
           static_cast<uint16_t>(column_idx);
       if (array_idx < array.size()) {
-        this->matrix[row_idx][column_idx] = array[array_idx];
+        this->matrix[row_idx * columns + column_idx] = array[array_idx];
       } else {
-        this->matrix[row_idx][column_idx] = 0;
+        this->matrix[row_idx * columns + column_idx] = 0;
       }
     }
   }
@@ -175,10 +174,9 @@ Matrix<rows, columns>::Transpose(Matrix<columns, rows> &result) const {
 // explicitly define the determinant for a 2x2 matrix because it is definitely
 // the fastest way to calculate a 2x2 matrix determinant
 template <> float Matrix<0, 0>::Det() const { return 1e+6; }
-template <> float Matrix<1, 1>::Det() const { return this->matrix[0][0]; }
+template <> float Matrix<1, 1>::Det() const { return this->matrix[0]; }
 template <> float Matrix<2, 2>::Det() const {
-  return this->matrix[0][0] * this->matrix[1][1] -
-         this->matrix[0][1] * this->matrix[1][0];
+  return this->matrix[0] * this->matrix[3] - this->matrix[1] * this->matrix[2];
 }
 
 template <uint8_t rows, uint8_t columns>
@@ -191,7 +189,7 @@ float Matrix<rows, columns>::Det() const {
   for (uint8_t column_idx{0}; column_idx < columns; column_idx++) {
     // for odd indices the sign is negative
     float sign = (column_idx % 2 == 0) ? 1 : -1;
-    determinant += sign * this->matrix[0][column_idx] *
+    determinant += sign * this->matrix[column_idx] *
                    this->MinorMatrix(MinorMatrix, 0, column_idx).Det();
   }
 
@@ -233,14 +231,15 @@ float Matrix<rows, columns>::Get(uint8_t row_index,
     return 1e+10; // TODO: We should throw something here instead of failing
                   // quietly
   }
-  return this->matrix[row_index][column_index];
+  return this->matrix[row_index * columns + column_index];
 }
 
 template <uint8_t rows, uint8_t columns>
 Matrix<1, columns> &
 Matrix<rows, columns>::GetRow(uint8_t row_index,
                               Matrix<1, columns> &row) const {
-  row = Matrix<1, columns>(this->matrix[row_index]);
+  memcpy(&(row[0]), this->matrix.begin() + row_index * columns,
+         columns * sizeof(float));
 
   return row;
 }
@@ -261,7 +260,8 @@ void Matrix<rows, columns>::ToString(std::string &stringBuffer) const {
   for (uint8_t row_idx{0}; row_idx < rows; row_idx++) {
     stringBuffer += "|";
     for (uint8_t column_idx{0}; column_idx < columns; column_idx++) {
-      stringBuffer += std::to_string(this->matrix[row_idx][column_idx]);
+      stringBuffer +=
+          std::to_string(this->matrix[row_idx * columns + column_idx]);
       if (column_idx != columns - 1) {
         stringBuffer += "\t";
       }
@@ -274,10 +274,13 @@ template <uint8_t rows, uint8_t columns>
 std::array<float, columns> &Matrix<rows, columns>::
 operator[](uint8_t row_index) {
   if (row_index > rows - 1) {
-    return this->matrix[0]; // TODO: We should throw something here instead of
-                            // failing quietly.
+    // TODO: We should throw something here instead of failing quietly.
+    row_index = 0;
   }
-  return this->matrix[row_index];
+  // cursed reinterpret_cast that will help us fake having a nested array when
+  // we really don't
+  return *reinterpret_cast<std::array<float, columns> *>(
+      &(this->matrix[row_index * columns]));
 }
 
 template <uint8_t rows, uint8_t columns>
@@ -285,7 +288,8 @@ Matrix<rows, columns> &Matrix<rows, columns>::
 operator=(const Matrix<rows, columns> &other) {
   for (uint8_t row_idx{0}; row_idx < rows; row_idx++) {
     for (uint8_t column_idx{0}; column_idx < columns; column_idx++) {
-      this->matrix[row_idx][column_idx] = other.Get(row_idx, column_idx);
+      this->matrix[row_idx * columns + column_idx] =
+          other.Get(row_idx, column_idx);
     }
   }
   // return a reference to ourselves so you can chain together these functions
@@ -351,7 +355,7 @@ template <uint8_t rows, uint8_t columns>
 void Matrix<rows, columns>::Fill(float value) {
   for (uint8_t row_idx{0}; row_idx < rows; row_idx++) {
     for (uint8_t column_idx{0}; column_idx < columns; column_idx++) {
-      this->matrix[row_idx][column_idx] = value;
+      this->matrix[row_idx * columns + column_idx] = value;
     }
   }
 }

Matrix.hpp

@@ -198,7 +198,7 @@ private:
 
   void setMatrixToArray(const std::array<float, rows * columns> &array);
 
-  std::array<std::array<float, columns>, rows> matrix;
+  std::array<float, rows * columns> matrix;
 };
 
 #include "Matrix.cpp"

unit-tests/matrix-test-timings.txt

@@ -1,14 +1,14 @@
-Addition: 0.55 s
-Subtraction: 0.548 s
-Multiplication: 3.404 s
-Scalar Multiplication: 0.453 s
-Element Multiply: 0.347 s
-Element Divide: 0.347 s
-Minor Matrix: 0.44 s
-Determinant: 0.251 s
-Matrix of Minors: 1.044 s
-Invert: 0.262 s
-Transpose: 0.26 s
-Normalize: 0.333 s
-GET ROW: 0.683 s
-GET COLUMN: 0.427 s
+Addition: 0.419 s
+Subtraction: 0.421 s
+Multiplication: 3.297 s
+Scalar Multiplication: 0.329 s
+Element Multiply: 0.306 s
+Element Divide: 0.302 s
+Minor Matrix: 0.331 s
+Determinant: 0.177 s
+Matrix of Minors: 0.766 s
+Invert: 0.183 s
+Transpose: 0.215 s
+Normalize: 0.315 s
+GET ROW: 0.008 s
+GET COLUMN: 0.43 s

unit-tests/test-timing-post-process.py

@@ -83,7 +83,7 @@ for new_timing in new_timings:
     for old_timing in old_timings:
         if new_timing == old_timing:
             new_timing.difference = new_timing - old_timing
-            if new_timing.difference >= 0.03:
+            if abs(new_timing.difference) >= 0.03:
                 difference_increased += f"{new_timing.test_name}, "
 
 def save_option():
@@ -102,7 +102,7 @@ for timing in new_timings:
     print(timing.to_string_w_diff())
 
 if len(difference_increased) > 0:
-    print("You increased the time it takes to run for:" + difference_increased)
+    print("You've made major timing changes for:" + difference_increased)
     save_option()
 else:
     print("No times have changed outside the margin of error.")