- class torch.optim.LBFGS(params, lr=1, max_iter=20, max_eval=None, tolerance_grad=1e-07, tolerance_change=1e-09, history_size=100, line_search_fn=None)¶
Implements L-BFGS algorithm, heavily inspired by minFunc.
This optimizer doesn’t support per-parameter options and parameter groups (there can be only one).
Right now all parameters have to be on a single device. This will be improved in the future.
This is a very memory intensive optimizer (it requires additional
param_bytes * (history_size + 1)bytes). If it doesn’t fit in memory try reducing the history size, or use a different algorithm.
lr (float) – learning rate (default: 1)
max_iter (int) – maximal number of iterations per optimization step (default: 20)
max_eval (int) – maximal number of function evaluations per optimization step (default: max_iter * 1.25).
tolerance_grad (float) – termination tolerance on first order optimality (default: 1e-5).
tolerance_change (float) – termination tolerance on function value/parameter changes (default: 1e-9).
history_size (int) – update history size (default: 100).
line_search_fn (str) – either ‘strong_wolfe’ or None (default: None).
Add a param group to the
This can be useful when fine tuning a pre-trained network as frozen layers can be made trainable and added to the
Optimizeras training progresses.
param_group (dict) – Specifies what Tensors should be optimized along with group specific optimization options.
Loads the optimizer state.
Returns the state of the optimizer as a
It contains two entries:
- state - a dict holding current optimization state. Its content
differs between optimizer classes.
- param_groups - a list containing all parameter groups where each
parameter group is a dict
Performs a single optimization step.
closure (Callable) – A closure that reevaluates the model and returns the loss.
Sets the gradients of all optimized
torch.Tensors to zero.
set_to_none (bool) – instead of setting to zero, set the grads to None. This will in general have lower memory footprint, and can modestly improve performance. However, it changes certain behaviors. For example: 1. When the user tries to access a gradient and perform manual ops on it, a None attribute or a Tensor full of 0s will behave differently. 2. If the user requests
zero_grad(set_to_none=True)followed by a backward pass,
.grads are guaranteed to be None for params that did not receive a gradient. 3.
torch.optimoptimizers have a different behavior if the gradient is 0 or None (in one case it does the step with a gradient of 0 and in the other it skips the step altogether).