Wuismeya

Hello, I want to reproduce the frequency clipping part, I encountered difficulties in implementing the inverse Fourier Transform, but I can't find the corresponding code in the [page](https://github.com/LeapLabTHU/EfficientTrain/commit/ef7d5f1c0951e6e625c40538e1802f86806256ca#diff-773b7e340b77c3c54109da863b41163ac971f899da59d8efcbfba7ce8a9c7e88R50)