enable_grad¶

class paddle. enable_grad [source]

Api_attr

imperative

Create a context which enable dygraph gradient calculation, if it has been disabled by no_grad or set_grad_enabled.

In this mode, the result of every computation will have stop_gradient set to False.

Also functions as a decorator. (Make sure to use an instance.)

Examples

>>> import paddle

>>> # use as generator

>>> x = paddle.to_tensor([1.], stop_gradient=False)
>>> with paddle.no_grad():
...     with paddle.enable_grad():
...         y = x * 2
>>> assert(y.stop_gradient == False)
>>> y.backward()
>>> assert(x.grad is not None)

>>> # use as decorator

>>> @paddle.enable_grad()
>>> def double(x):
...     return x * 2
...
>>> with paddle.no_grad():
...     z = double(x)
...
>>> assert(z.stop_gradient == False)