4 ms·
Genuinely curious - How does this save space? If the input was real, the first operation (inside the fft call) makes it complex, which doubles the storage space
by tails4e 4y ago
Genuinely curious - How does this save space? If the input was real, the first operation (inside the fft call) makes it complex, which doubles the storage space. Sure the output is real again, but the intermediate storage was 2x the input and output.
- sillysaurusx 4y agoSince the input is copied to the real and imaginary components, you don’t actually need to copy it at all. Think of it like having a pointer (in the C sense) to the real and imaginary image buffers. Set both pointers to the input signal, then run your FFT algo on that. The key is that it minimizes memory bandwidth, not computation. It’s highly cache coherent.
- tails4e 4y agoThanks, so the real and imag components always map to the same value during the processing, i.e. After every butterfly the real and iamg will be the same value? Cause again if the real and imag components ever differ it means more storage needed.
- sillysaurusx 4y agoCorrect, they are identical by definition.