diff --git a/matrix.cpp b/matrix.cpp
index 614c76c..abe8ecc 100644
--- a/matrix.cpp
+++ b/matrix.cpp
@@ -28,10 +28,18 @@ int main() {
 
   cout << "The matrix m:" << endl;
   cout << m << endl;
+  cout << "The determinant of matrix m:" << endl;
+  cout << m.determinant() << endl;
   cout << "The matrix m's transpose:" << endl;
   cout << m.transpose() << endl;
+  cout << "The matrix m's diagonal:" << endl;
+  cout << m.get_diagonal() << endl;
+  cout << "The matrix m's off diagonal:" << endl;
+  cout << m.get_off_diagonal() << endl;
   cout << "The matrix n" << endl;
   cout << n << endl;
+  cout << "The determinant of matrix n:" << endl;
+  cout << n.determinant() << endl;
   cout << "The matrix m * n" << endl;
   cout << m * n << endl;
   if  (!m.is_hermitian()) {
diff --git a/matrix.hpp b/matrix.hpp
index fc943ec..20bce4a 100644
--- a/matrix.hpp
+++ b/matrix.hpp
@@ -22,8 +22,19 @@ public:
   ~matrix() {
     this->num_cols = 0;
     this->num_rows = 0;
-    //    free(this->cols);
-    // this->cols = NULL;
+    free(this->cols);
+    this->cols = NULL;
+  }
+  const cnumber determinant() const {
+	  cnumber dsum(1,0);
+	  cnumber osum(1,0);
+	  vector diag = this->get_diagonal();
+	  vector odiag = this->get_off_diagonal();
+	  for (long long i = 0; i < diag.get_dimention(); i++) {
+		  dsum = dsum * diag[i];
+		  osum = osum * odiag[i];
+	  }
+	  return dsum - osum;
   }
   const vector get_diagonal() const {
     long long diag_len = this->num_rows;
@@ -40,6 +51,21 @@ public:
     }
     return v;
   }
+  const vector get_off_diagonal() const {
+    long long diag_len = this->num_rows;
+    if (this->num_cols < diag_len) {
+      diag_len = this->num_cols;
+    }
+    vector v(diag_len);
+    for (long long i = 0; i < this->num_cols; i++) {
+      for (long long j = 0; j < this->num_rows; j++) {
+        if (i + j == this->num_rows - 1) {
+          v[i] = this->cols[i][j];
+        }
+      }
+    }
+    return v;
+  }
   const vector get_row(long long index) const { return this->cols[index]; }
 
   const vector get_column(long long index) const {