[FEAT] Matrix : add minor

tests/03_matrix.cpp

@@ -277,3 +277,20 @@ TEST_CASE("[Matrix] A submatrix of a 4x4 matrix is a 3x3 matrix", "[Matrix]")
 
     REQUIRE(a.sub_matrix(2, 1) == b);
 }
+
+/* ------------------------------------------------------------------------- */
+
+TEST_CASE("[Matrix] Calculating a minor of a 3x3 matrix", "[Matrix]")
+{
+    Matrix a = {
+        {3,  5,  0},
+        {2, -1, -7},
+        {6, -1,  5}
+    };
+
+    Matrix b = a.sub_matrix(1, 0);
+
+    REQUIRE(b.determinant() == 25);
+
+    REQUIRE(a.minor(1, 0) == 25);
+}