message: Fix calculating pseudo-gradient in OWL-QN
diff: @@ -475,7 +475,7 @@ where
  self.s.push_back(xk1.sub(&param));
  let grad = if let Some(l1_coeff) = self.l1_coeff {
  // Stores unregularized gradient and returns L1 gradient.
  - let pseudo_grad = calculate_pseudo_gradient(l1_coeff, &param, &grad);
  + let pseudo_grad = calculate_pseudo_gradient(l1_coeff, &xk1, &grad);
  self.y
  .push_back(grad.sub(self.l1_prev_unreg_grad.as_ref().unwrap()));
  self.l1_prev_unreg_grad = Some(grad);
  