Some fixes to smooth_l1_loss (#45532)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45532
- updated documentation
- explicitly not supporting negative values for beta (previously the
result was incorrect)
- Removing default value for beta in the backwards function, since it's
only used internally by autograd (as per convention)
Test Plan: Imported from OSS
Reviewed By: gchanan
Differential Revision: D24002415
Pulled By: bdhirsh
fbshipit-source-id: 980c141019ec2d437b771ee11fc1cec4b1fcfb48
