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About the prameter FORWARD and BACKWARD #283

Closed Nakamotto closed 2 years ago

Nakamotto commented 2 years ago

As to the same fftw_complex *, FORWARD and BACKWARD give the same result when using fftw_plan_dft_2d. Thanks for your time in advance!

stevengj commented 2 years ago

Put in real inputs, for example. In that case you should notice that the FFTW_FORWARD and FFTW_BACKWARD results are complex conjugates.

(If you think they are giving the same results for all inputs, then you are misinterpreting the results or doing something wrong. That's not how DFTs work, and someone would have probably noticed 25 years ago if FFTW got something so basic wrong.)