Return 0-numel empty tensor from symeig when eigenvectors=False (#28338)
Summary:
Changelog:
- Changes the behavior of returning a zero tensor when eigenvectors=False, matching behavior of torch.eig
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28338
Test Plan: - test_symeig has been modified appropriately for this change
Differential Revision: D18085280
Pulled By: ezyang
fbshipit-source-id: 43129a96dd01743997157974100e5a7270742b46
