Added minor

matrix/src/lib.rs

@@ -51,7 +51,14 @@ impl<const H: usize, const W: usize> Matrix<H, W> {
         self.matrix[0][0] * self.matrix[1][1] - self.matrix[0][1] * self.matrix[1][0]
     }
 
-    pub fn sub_matrix(&self, skip_row: usize, skip_col: usize) -> Matrix<{H - 1}, {W - 1}> 
+    pub fn minor(&self, row: usize, col: usize) -> f32 where
+        [(); H - 1]: ,
+        [(); W - 1]: ,
+    {
+        self.sub_matrix(row, col).determinant()
+    }
+
+    pub fn sub_matrix(&self, skip_row: usize, skip_col: usize) -> Matrix<{H - 1}, {W - 1}>
     {
         let mut idx_row: usize = 0;
 
@@ -391,4 +398,18 @@ mod tests {
 
         assert_eq!(expected, start.sub_matrix(2, 1));
     }
+
+    #[test]
+    fn minor_3x3() {
+        let m = Matrix::from_array([
+            [3.0, 5.0, 0.0],
+            [2.0, -1.0, -7.0],
+            [6.0, -1.0, 5.0],
+        ]);
+
+        let s = m.sub_matrix(1, 0);
+
+        assert_eq!(25.0, s.determinant());
+        assert_eq!(25.0, m.minor(1, 0));
+    }
 }