Port SVD to ATen, enable batching for matrix inputs (#21588)
Summary:
Changelog:
- Port SVD TH implementation to ATen/native/BatchLinearAlgebra.cpp
- Port SVD THC implementation to ATen/native/cuda/BatchLinearAlgebra.cu
- Allow batches of matrices as arguments to `torch.svd`
- Remove existing implementations in TH and THC
- Update doc string
- Update derivatives to support batching
- Modify nuclear norm implementation to use at::svd instead of _batch_svd
- Remove _batch_svd as it is redundant
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21588
Test Plan:
- Add new test suite for SVD in test_torch.py with port to test_cuda.py
- Add tests in common_methods_invocations.py for derivative testing
Differential Revision: D16266115
Pulled By: nairbv
fbshipit-source-id: e89bb0dbd8f2d58bd758b7830d2389c477aa61fb
