From 64820553c7e77c833a76c3a6aab28c7c012cdc69 Mon Sep 17 00:00:00 2001
From: Cynopolis <quinn.henthorne@gmail.com>
Date: Mon, 2 Jun 2025 16:19:23 -0400
Subject: [PATCH] New norms and division by scalar

---
 src/Matrix.cpp                     | 42 +++++++++++++++++++-----------
 src/Matrix.hpp                     |  6 ++++-
 src/Quaternion.cpp                 |  3 +--
 unit-tests/matrix-tests.cpp        | 10 ++++---
 unit-tests/matrix-timing-tests.cpp |  2 +-
 5 files changed, 40 insertions(+), 23 deletions(-)

diff --git a/src/Matrix.cpp b/src/Matrix.cpp
index 570ee84..f253d89 100644
--- a/src/Matrix.cpp
+++ b/src/Matrix.cpp
@@ -337,6 +337,22 @@ Matrix<rows, columns> Matrix<rows, columns>::operator*(float scalar) const {
   return buffer;
 }
 
+template <uint8_t rows, uint8_t columns>
+Matrix<rows, columns> Matrix<rows, columns>::operator/(float scalar) const {
+  Matrix<rows, columns> buffer = *this;
+  if (scalar == 0) {
+    buffer.Fill(1e+10);
+    return buffer;
+  }
+
+  for (uint8_t row = 0; row < rows; row++) {
+    for (uint8_t column = 0; column < columns; column++) {
+      buffer[row][column] /= scalar;
+    }
+  }
+  return buffer;
+}
+
 template <uint8_t rows, uint8_t columns>
 template <uint8_t vector_size>
 float Matrix<rows, columns>::DotProduct(const Matrix<1, vector_size> &vec1,
@@ -423,7 +439,7 @@ Matrix<rows, columns>::adjugate(Matrix<rows, columns> &result) const {
 }
 
 template <uint8_t rows, uint8_t columns>
-Matrix<rows, columns> Matrix<rows, columns>::EuclideanNorm() const {
+float Matrix<rows, columns>::EuclideanNorm() const {
 
   float sum{0};
   for (uint8_t row_idx{0}; row_idx < rows; row_idx++) {
@@ -433,21 +449,17 @@ Matrix<rows, columns> Matrix<rows, columns>::EuclideanNorm() const {
     }
   }
 
-  Matrix<rows, columns> result{};
-  if (sum == 0) {
-    // this wouldn't do anything anyways
-    result.Fill(0);
-    return result;
+  return sqrt(sum);
+}
+template <uint8_t rows, uint8_t columns>
+float Matrix<rows, columns>::L2Norm() const {
+  float sum{0};
+  Matrix<rows, 1> columnMatrix{};
+  for (uint8_t column = 0; column < columns; column++) {
+    this.GetColumn(column, columnMatrix);
+    sum += columnMatrix.EuclideanNorm();
   }
-
-  sum = sqrt(sum);
-  for (uint8_t row_idx{0}; row_idx < rows; row_idx++) {
-    for (uint8_t column_idx{0}; column_idx < columns; column_idx++) {
-      result[row_idx][column_idx] = this->Get(row_idx, column_idx) / sum;
-    }
-  }
-
-  return result;
+  return sqrt(sum);
 }
 
 template <uint8_t rows, uint8_t columns>
diff --git a/src/Matrix.hpp b/src/Matrix.hpp
index b7ea1b9..0abd9b1 100644
--- a/src/Matrix.hpp
+++ b/src/Matrix.hpp
@@ -132,7 +132,9 @@ public:
    * @brief reduce the matrix so the sum of its elements equal 1
    * @param result a buffer to store the result into
    */
-  Matrix<rows, columns> EuclideanNorm() const;
+  float EuclideanNorm() const;
+
+  float L2Norm() const;
 
   /**
    * @brief Get a row from the matrix
@@ -201,6 +203,8 @@ public:
 
   Matrix<rows, columns> operator*(float scalar) const;
 
+  Matrix<rows, columns> operator/(float scalar) const;
+
   template <uint8_t sub_rows, uint8_t sub_columns, uint8_t row_offset,
             uint8_t column_offset>
   Matrix<sub_rows, sub_columns> SubMatrix() const;
diff --git a/src/Quaternion.cpp b/src/Quaternion.cpp
index 204896d..a946659 100644
--- a/src/Quaternion.cpp
+++ b/src/Quaternion.cpp
@@ -9,8 +9,7 @@
 Quaternion Quaternion::FromAngleAndAxis(float angle, const Matrix<1, 3> &axis) {
   const float halfAngle = angle / 2;
   const float sinHalfAngle = sin(halfAngle);
-  Matrix<1, 3> normalizedAxis{};
-  normalizedAxis = axis.EuclideanNorm();
+  Matrix<1, 3> normalizedAxis = axis / axis.EuclideanNorm();
   return Quaternion{static_cast<float>(cos(halfAngle)),
                     normalizedAxis.Get(0, 0) * sinHalfAngle,
                     normalizedAxis.Get(0, 1) * sinHalfAngle,
diff --git a/unit-tests/matrix-tests.cpp b/unit-tests/matrix-tests.cpp
index fb0575e..f218b6b 100644
--- a/unit-tests/matrix-tests.cpp
+++ b/unit-tests/matrix-tests.cpp
@@ -373,13 +373,15 @@ float matrixSum(const Matrix<rows, columns> &matrix) {
   return std::sqrt(sum);
 }
 
+// TODO: Add test for scalar division
+
 TEST_CASE("Normalization", "Matrix") {
 
   SECTION("2x2 Normalize") {
     Matrix<2, 2> mat1{1, 2, 3, 4};
     Matrix<2, 2> mat2{};
 
-    mat2 = mat1.EuclideanNorm();
+    mat2 = mat1 / mat1.EuclideanNorm();
 
     float sqrt_30{static_cast<float>(sqrt(30.0f))};
 
@@ -394,7 +396,7 @@ TEST_CASE("Normalization", "Matrix") {
   SECTION("2x1 (Vector) Normalize") {
     Matrix<2, 1> mat1{-0.878877044, 2.92092276};
     Matrix<2, 1> mat2{};
-    mat2 = mat1.EuclideanNorm();
+    mat2 = mat1 / mat1.EuclideanNorm();
 
     REQUIRE_THAT(mat2.Get(0, 0),
                  Catch::Matchers::WithinRel(-0.288129855179f, 1e-6f));
@@ -408,13 +410,13 @@ TEST_CASE("Normalization", "Matrix") {
   SECTION("Normalized vectors sum to 1") {
     Matrix<9, 1> mat1{1, 2, 3, 4, 5, 6, 7, 8, 9};
     Matrix<9, 1> mat2;
-    mat2 = mat1.EuclideanNorm();
+    mat2 = mat1 / mat1.EuclideanNorm();
     float sum = matrixSum(mat2);
     REQUIRE_THAT(sum, Catch::Matchers::WithinRel(1.0f, 1e-6f));
 
     Matrix<2, 3> mat3{1, 2, 3, 4, 5, 6};
     Matrix<2, 3> mat4{};
-    mat4 = mat3.EuclideanNorm();
+    mat4 = mat3 / mat3.EuclideanNorm();
     sum = matrixSum(mat4);
     REQUIRE_THAT(sum, Catch::Matchers::WithinRel(1.0f, 1e-6f));
   }
diff --git a/unit-tests/matrix-timing-tests.cpp b/unit-tests/matrix-timing-tests.cpp
index c48802f..9c01347 100644
--- a/unit-tests/matrix-timing-tests.cpp
+++ b/unit-tests/matrix-timing-tests.cpp
@@ -99,7 +99,7 @@ TEST_CASE("Timing Tests", "Matrix") {
 
   SECTION("Normalize") {
     for (uint32_t i{0}; i < 10000; i++) {
-      mat3 = mat1.EuclideanNorm();
+      mat3 = mat1 / mat1.EuclideanNorm();
     }
   }