Use better machinery for is_hermitian

matrix.hpp

@@ -147,16 +147,7 @@ public:
   const bool is_hermitian() const {
     if (this->entry_dimension != this->num_entries)
       return false;
-    matrix m = this->hermitian_conjugate();
-    bool equal = true;
-    for (long long i = 0; i < m.num_entries; i++) {
-      for (long long j = 0; j < m.entry_dimension; j++) {
-        if (m[i][j] != this->entries[i][j]) {
-          equal = false;
-        }
-      }
-    }
-    return equal;
+    return *this == this->hermitian_conjugate();
   }
   friend ostream &operator<<(ostream &os, const matrix &m) {
     char last = '\0';