garage.torch.optimizers.differentiable_sgd

Differentiable Stochastic Gradient Descent Optimizer.

Useful for algorithms such as MAML that needs the gradient of functions of post-updated parameters with respect to pre-updated parameters.

class DifferentiableSGD(module, lr=0.001)

Differentiable Stochastic Gradient Descent.

DifferentiableSGD performs the same optimization step as SGD, but instead of updating parameters in-place, it saves updated parameters in new tensors, so that the gradient of functions of new parameters can flow back to the pre-updated parameters.

Parameters

• module (torch.nn.module) – A torch module whose parameters needs to be optimized.

• lr (float) – Learning rate of stochastic gradient descent.

step()

Take an optimization step.

zero_grad()

Sets gradients of all model parameters to zero.

set_grads_none()

Sets gradients for all model parameters to None.

This is an alternative to zero_grad which sets gradients to zero.