3063 Fix the complex Tensor issue in type conversion

[Nic-Ma]

Fixes #3063 .

Description

This PR fixed the issue that PyTorch 1.5.1 can't support complex Tensor.

Status

Ready

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.

[Nic-Ma]

/black

[Nic-Ma]

Tested this PR in PyTorch 1.5.1:

root@apt-sh-ai:/workspace/data/medical/MONAI# python
Python 3.8.10 | packaged by conda-forge | (default, May 11 2021, 07:01:05)
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import torch
>>> print(torch.__version__)
1.5.1
>>> exit()
root@apt-sh-ai:/workspace/data/medical/MONAI# python tests/test_k_space_spike_noised.py
..................
----------------------------------------------------------------------
Ran 18 tests in 3.938s

OK

[Nic-Ma]

/black

[wyli]

/build

[wyli]

Thanks, it looks good to me.