From f24280c866669f579139480e31921dd8c4cb9865 Mon Sep 17 00:00:00 2001
From: Jon Janzen <jonjanzen@me.com>
Date: Sun, 28 Mar 2021 18:00:15 -0600
Subject: [PATCH] matrix with equality

---
 matrix/Cargo.toml |  1 +
 matrix/src/lib.rs | 96 ++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 96 insertions(+), 1 deletion(-)

diff --git a/matrix/Cargo.toml b/matrix/Cargo.toml
index 18c3018..2f6e9d1 100644
--- a/matrix/Cargo.toml
+++ b/matrix/Cargo.toml
@@ -7,3 +7,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+approx = "0.4"
diff --git a/matrix/src/lib.rs b/matrix/src/lib.rs
index 967c69e..378d3d1 100644
--- a/matrix/src/lib.rs
+++ b/matrix/src/lib.rs
@@ -1,5 +1,9 @@
+#[macro_use]
+extern crate approx;
+
 use std::ops::Index;
 
+#[derive(Debug)]
 pub struct Matrix {
     matrix: Vec<Vec<f32>>,
 }
@@ -19,12 +23,32 @@ impl Index<usize> for Matrix {
     }
 }
 
+impl PartialEq for Matrix {
+    fn eq(&self, _rhs: &Self) -> bool {
+        if self.matrix.len() != _rhs.matrix.len() {
+            return false;
+        }
+        
+        for row_idx in 0..self.matrix.len() {
+            if self.matrix[row_idx].len() != _rhs.matrix[row_idx].len() {
+                return false;
+            }
+            for col_idx in 0..self.matrix[row_idx].len() {
+                if !relative_eq!(self.matrix[row_idx][col_idx], _rhs.matrix[row_idx][col_idx]) {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
     #[test]
-    fn it_works() {
+    fn matrix_4x4() {
         let m = vec![
             vec![1.0, 2.0, 3.0, 4.0],
             vec![5.5, 6.5, 7.5, 8.5],
@@ -42,4 +66,74 @@ mod tests {
         assert_eq!(15.5,  matrix[3][2]);
     }
 
+    #[test]
+    fn matrix_2x2() {
+        let m = vec![
+            vec![-3.0, 5.0,],
+            vec![1.0, 2.0,],
+        ];
+        let matrix = Matrix::new(m);
+        assert_eq!(-3.0, matrix[0][0]);
+        assert_eq!(5.0, matrix[0][1]);
+        assert_eq!(1.0, matrix[1][0]);
+        assert_eq!(2.0, matrix[1][1]);
+    }
+
+    #[test]
+    fn matrix_3x3() {
+        let m = vec![
+            vec![-3.0, 5.0, 0.0],
+            vec![1.0, -2.0, -7.0],
+            vec![0.0, 1.0, 1.0],
+        ];
+
+        let matrix = Matrix::new(m);
+        assert_eq!(-3.0, matrix[0][0]);
+        assert_eq!(-2.0, matrix[1][1]);
+        assert_eq!(1.0, matrix[2][2]);
+    }
+
+    #[test]
+    fn matrix_equality_a() {
+        let a = vec![
+            vec![1.0, 2.0, 3.0, 4.0],
+            vec![5.0, 6.0, 7.0, 8.0],
+            vec![9.0, 8.0, 7.0, 6.0],
+            vec![5.0, 4.0, 3.0, 2.0],
+        ];
+        let m_a = Matrix::new(a);
+            
+        let b = vec![
+            vec![1.0, 2.0, 3.0, 4.0],
+            vec![5.0, 6.0, 7.0, 8.0],
+            vec![9.0, 8.0, 7.0, 6.0],
+            vec![5.0, 4.0, 3.0, 2.0],
+        ];
+
+        let m_b = Matrix::new(b);
+
+        assert_eq!(m_a, m_b);
+    }
+
+    #[test]
+    fn matrix_equality_b() {
+        let a = vec![
+            vec![1.0, 2.0, 3.0, 4.0],
+            vec![5.0, 6.0, 7.0, 8.0],
+            vec![9.0, 8.0, 7.0, 6.0],
+            vec![5.0, 4.0, 3.0, 2.0],
+        ];
+        let m_a = Matrix::new(a);
+            
+        let b = vec![
+            vec![2.0, 3.0, 4.0, 5.0],
+            vec![6.0, 7.0, 8.0, 9.0],
+            vec![8.0, 7.0, 6.0, 5.0],
+            vec![4.0, 3.0, 2.0, 1.0],
+        ];
+
+        let m_b = Matrix::new(b);
+
+        assert_ne!(m_a, m_b);
+    }
 }