From b991153b8b955313d928b31860cf7fa1825dbd6a Mon Sep 17 00:00:00 2001
From: Pascal Serrarens <pascal@passervr.com>
Date: Wed, 12 Feb 2025 11:38:15 +0100
Subject: [PATCH] Add ChiSquareTest

---
 LinearAlgebra/Matrix.cs | 122 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)

diff --git a/LinearAlgebra/Matrix.cs b/LinearAlgebra/Matrix.cs
index 60d260b..1960109 100644
--- a/LinearAlgebra/Matrix.cs
+++ b/LinearAlgebra/Matrix.cs
@@ -1,5 +1,127 @@
+using System.Diagnostics;
 using Vector3 = UnityEngine.Vector3;
 
+public class Matrix2 {
+    public float[,] data { get; }
+
+    public int nRows => data.GetLength(0);
+    public int nCols => data.GetLength(1);
+
+    public Matrix2(float[,] data) {
+        this.data = data;
+    }
+
+    public static Matrix2 Identity(int size) {
+        float[,] I = new float[size, size];
+        for (int i = 0; i < size; i++) I[i, i] = 1.0f;
+        return new Matrix2(I);
+    }
+
+    public Matrix2 Transpose() {
+        float[,] r = new float[this.nCols, this.nRows];
+        for (uint rowIx = 0; rowIx < this.nRows; rowIx++) {
+            for (uint colIx = 0; colIx < this.nCols; colIx++)
+                r[colIx, rowIx] = this.data[rowIx, colIx];
+        }
+        return new Matrix2(r);
+        // double checked code
+    }
+
+    public static Matrix2 operator +(Matrix2 A, Matrix2 B) {
+        if (A.nRows != B.nRows || A.nCols != B.nCols)
+            throw new System.ArgumentException("Size of A must match size of B.");
+
+        float[,] result = new float[A.nRows, B.nCols];
+
+        for (int i = 0; i < A.nRows; i++) {
+            for (int j = 0; j < A.nCols; j++) {
+                result[i, j] = A.data[i, j] + B.data[i, j];
+            }
+        }
+        return new Matrix2(result);
+    }
+
+    public static Matrix2 operator *(Matrix2 A, Matrix2 B) {
+        if (A.nCols != B.nRows)
+            throw new System.ArgumentException("Number of columns in A must match number of rows in B.");
+
+        float[,] result = new float[A.nRows, B.nCols];
+
+        for (int i = 0; i < A.nRows; i++) {
+            for (int j = 0; j < B.nCols; j++) {
+                float sum = 0.0f;
+                for (int k = 0; k < A.nCols; k++)
+                    sum += A.data[i, k] * B.data[k, j];
+
+                result[i, j] = sum;
+            }
+        }
+
+        return new Matrix2(result);
+        // double checked code
+    }
+
+    public static Matrix1 operator *(Matrix2 A, Matrix1 v) {
+        // int rows = A.GetLength(0);
+        // int cols = A.GetLength(1);
+        float[] result = new float[A.nRows];
+
+        for (int i = 0; i < A.nRows; i++) {
+            for (int j = 0; j < A.nCols; j++) {
+                result[i] += A.data[i, j] * v.data[j];
+            }
+        }
+
+        return new Matrix1(result);
+    }
+
+
+    public static Matrix2 operator *(Matrix2 A, float s) {
+        float[,] result = new float[A.nRows, A.nCols];
+
+        for (int i = 0; i < A.nRows; i++) {
+            for (int j = 0; j < A.nCols; j++)
+                result[i, j] += A.data[i, j] * s;
+        }
+
+        return new Matrix2(result);
+    }
+    public static Matrix2 operator *(float scalar, Matrix2 A) {
+        return A * scalar;
+    }
+
+}
+
+public class Matrix1 {
+    public float[] data { get; }
+
+    public int size => data.GetLength(0);
+
+    public Matrix1(float[] data) {
+        this.data = data;
+    }
+
+    public Matrix2 Transpose() {
+        float[,] r = new float[1, this.size];
+        for (uint colIx = 0; colIx < this.size; colIx++)
+            r[1, colIx] = this.data[colIx];
+
+        return new Matrix2(r);
+    }
+
+    public static float Dot(Matrix1 a, Matrix1 b) {
+        if (a.size != b.size)
+            throw new System.ArgumentException("Vectors must be of the same length.");
+
+        float result = 0.0f;
+        for (int i = 0; i < a.size; i++) {
+            result += a.data[i] * b.data[i];
+        }
+        return result;
+    }
+
+}
+
 public class Matrix {
     private readonly uint rows = 0;
     private readonly uint cols = 0;