change grad to velocity_vec variable

Author: loki-veera

src/optimize_2d_momentum_bumpy.py

@@ -64,7 +64,7 @@ def bumpy_grad(pos: np.ndarray) -> np.ndarray:
     step_total = 1  # TODO: Choose the total number of steps.
 
     pos_list = [start_pos]
-    grad = np.array((0.0, 0.0))
+    velocity_vec = np.array((0.0, 0.0))
     # TODO implement gradient descent with momentum.
 
     for pos in pos_list:

src/optimize_2d_momentum_bumpy_jax.py

@@ -57,7 +57,7 @@ def bumpy_function(pos: np.ndarray) -> np.ndarray:
     step_total = 100
 
     pos_list = [start_pos]
-    grad = np.array((0.0, 0.0))
+    velocity_vec = np.array((0.0, 0.0))
     # TODO: Implement gradient descent with momentum.
 
     for pos in pos_list: