Zoom Fast Fourier Transform and Chirp Z-Transform #178
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@@ Coverage Diff @@
## master #178 +/- ##
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+ Coverage 81.28% 81.45% +0.16%
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Files 96 98 +2
Lines 7182 7273 +91
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+ Hits 5838 5924 +86
- Misses 1344 1349 +5
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Also modify the thresholds since the ZoomFFT is not really accurate.
This line should be disabled when support for Python 3.7 is dropped.
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@syhaffert This is still waiting for your review, and is now blocking another PR that I'm working on. |
syhaffert
reviewed
Apr 20, 2023
syhaffert
reviewed
Apr 20, 2023
syhaffert
approved these changes
Apr 20, 2023
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The ZoomFFT is a Fourier transform based on the chirp Z-transform. Asymptotically it is faster than the MFT - since it's implemented using FFTs, its complexity is O(N^2 log(N)) for 2D transforms - the point of equality is only reached at array sizes of 1k x 1k (input) to 1k x 1k (output) or larger.
This Fourier transform will be added to the
make_fourier_transform()function with a later PR. This PR is just for adding its implementation and the tests to support it long term.One short-term caveat for the tests: the chirp Z-transform is tested by comparing with the scipy implementation of the CZT. We're not using that implementation since the FFTs that it uses are not accelerated. However, the scipy implementation is only available from version 1.8.0 onwards, which does not support Python 3.7. Therefore, I had to disable the CZT tests when scipy >=1.8.0 is not installed, so only on Python 3.8+. This caveat will be resolved when support for Python 3.7 will be dropped from HCIPy.