Added type promotion logic for complex numbers (#34093)
Summary:
Issue: https://github.com/pytorch/pytorch/issues/33780
After this PR:
1. dtype promotion logic will correctly work for ops involving complex scalars
2. torch.ComplexFloatTensor, torch.ComplexDoubleTensor works
3. added alias for complex64 (cfloat) and complex128 (cdouble)
4. added an internal function get_complex_default_dtype (consciously not exposed in public API)
>>> 1j*torch.ones(2)
tensor([(0.0000 + 1.0000j), (0.0000 + 1.0000j)], dtype=torch.complex64)
>>> torch.set_default_dtype(torch.float64)
>>> 1j*torch.ones(2)
tensor([(0.0000 + 1.0000j), (0.0000 + 1.0000j)], dtype=torch.complex128)
>>> 1j + torch.ones(2)
tensor([(1.0000 + 1.0000j), (1.0000 + 1.0000j)], dtype=torch.complex128)
>>> torch.tensor(1j) + torch.ones(2,2)
tensor([[(1.0000 + 1.0000j), (1.0000 + 1.0000j)],
[(1.0000 + 1.0000j), (1.0000 + 1.0000j)]], dtype=torch.complex128)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34093
Differential Revision: D20312366
Pulled By: anjali411
fbshipit-source-id: 90f00a1a916d9c8eeda101eb6e9d250fce569815
