[functorch] modified example

functorch/README.md

@@ -105,20 +105,21 @@ When composed with `vmap`, `grad` can be used to compute per-sample-gradients:
 ```py
 >>> from functorch import vmap
 >>> batch_size, feature_size = 3, 5
->>> weights = torch.randn(feature_size, requires_grad=True)
 >>>
->>> def model(feature_vec):
+>>> def model(weights,feature_vec):
 >>>     # Very simple linear model with activation
 >>>     assert feature_vec.dim() == 1
 >>>     return feature_vec.dot(weights).relu()
 >>>
 >>> def compute_loss(weights, example, target):
->>>     y = model(example)
->>>     return ((y - t) ** 2).mean()  # MSELoss
+>>>     y = model(weights, example)
+>>>     return ((y - target) ** 2).mean()  # MSELoss
 >>>
+>>> weights = torch.randn(feature_size, requires_grad=True)
 >>> examples = torch.randn(batch_size, feature_size)
 >>> targets = torch.randn(batch_size)
->>> grad_weight_per_example = vmap(grad(compute_loss))(weights, examples, targets)
+>>> inputs = (weights,examples, targets)
+>>> grad_weight_per_example = vmap(grad(compute_loss), in_dims=(None, 0, 0))(*inputs)
 ```
 
 ### vjp and jacrev
@@ -149,8 +150,8 @@ batched jacobians:
 `jacrev` can be composed with itself to produce hessians:
 ```py
 >>> def f(x):
->>>   return x.sin().sum() 
->>> 
+>>>   return x.sin().sum()
+>>>
 >>> x = torch.randn(5)
 >>> hessian = jacrev(jacrev(f))(x)
 ```