isLowerTriangular method

Implementation

bool isLowerTriangular([double tolerance = 1e-10]) {
  for (int i = 0; i < rowCount - 1; i++) {
    for (int j = i + 1; j < columnCount; j++) {
      if (this[i][j].abs() > tolerance) {
        return false;
      }
    }
  }
  return true;
}