get action in sac_continuous_action.py about cleanrl HOT 2 OPEN

Thanks for your generous help @Howuhh. Is 1e-6 meant to limit the logarithmic value to approach negative infinity?

from cleanrl.

Usually in SAC we use Normal distribution coupled with tanh to bound action space. However, after such transformation the actual distribution is now not just standard Normal and we can not use it's lob_prob to get the probabilities of actions. This formula accounts for the transformation and gives right probabilities for TanhNormal distribution. See Appendix C in the original paper: https://arxiv.org/pdf/1801.01290.pdf

from cleanrl.