torchrl.objectives.symlog

torchrl.objectives.symlog(x: Tensor) → Tensor

Symmetric logarithm: sign(x) * log(|x| + 1).

Used by DreamerV3 to compress the dynamic range of targets and predictions before computing reconstruction losses.

Reference: https://arxiv.org/abs/2301.04104

Parameters:

x – Input tensor.

Returns:

Tensor of the same shape as x.

Examples

>>> import torch
>>> from torchrl.objectives import symlog
>>> x = torch.tensor([-100.0, 0.0, 100.0])
>>> symlog(x)
tensor([-4.6151,  0.0000,  4.6151])