Small update to notebook 5

docs/examples/05_Plane_wave_expansion_with_autograd.ipynb

@@ -347,7 +347,7 @@
    "source": [
     "## Optimize the waveguide\n",
     "\n",
-    "For the optimization, we will use the autograd function `obj_and_grad`, which returns the value of the objective function and the gradients simultaneously. Note that `legume` comes with a `Minimize` class that implements either `adam` or `lbfgs` minimization, which is what we are going to use. Of course, any external optimization function can also be combined with the gradient computation from `legume` (in fact, the `lbfgs` minimizer is a wrapper around the `SciPy` implementation). "
+    "For the optimization, we will use the `Minimize` class provided with `legume`, which implements either `adam` or `lbfgs` minimization. The `lbfgs` minimizer is just a wrapper around the `SciPy` implementation, and any external optimization function can also be combined with the gradient computation from `legume`. Note that `autograd` provides both a `grad` function as used above, and an `obj_and_grad` function that returns simultaneously the value and the gradient of the objective function, which can be useful for custom optimization functions."
    ]
   },
   {
@@ -447,7 +447,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.3"
+   "version": "3.8.5"
   }
  },
  "nbformat": 4,