Makes torch.real and torch.imag NumPy compatible, but disables them for complex tensors (#35560)
Summary:
The current implementations of torch.real and torch.imag are not NumPy compatible. In particular:
- torch.real on a real tensor does not return the real tensor, like contiguous
- torch.real on a complex tensor does not return a real-valued view of the real part
- torch.imag on a complex tensor does not return a real-valued view of the imaginary part
- torch.Tensor.real and torch.Tensor.imag exist as methods, but in NumPy they are writable attributes
This PR makes the functions NumPy compatible by removing the method variants and out kwarg, restricting them to work on only real tensors, and updating the behavior of torch.real to return its input. New tests are added to test_torch.py to verify the behavior, a couple existing complex tests are skipped, and the documentation is updated to reflect the change.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35560
Differential Revision: D20714568
Pulled By: mruberry
fbshipit-source-id: 5dd092f45757b620c8426c829dd15ee997246a26
