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I often see these "plot the output of the RNG on a 2d grid" things. I understand they're useful for demonstrating non-randomness, but if you're searching for pa
by bcoates 13y ago
I often see these "plot the output of the RNG on a 2d grid" things. I understand they're useful for demonstrating non-randomness, but if you're searching for patterns, do they reveal anything an FFT wouldn't?
- baq 13y agoisn't fft just a different way of looking at the data?
- USNetizen 13y agoEssentially, yes, that was my understanding, too. I've only used in in signal processing - converting from the time domain to the frequency domain. Not sure how that would apply to this.
- bcoates 13y agoI was thinking specifically of this: When i look at the FNV-1a "number" map, i think i see subtle vertical patterns. With Murmur i see no patterns at all. What do you think? Wouldn't that vertical repetition, and the other repeating patterns the other hashes form, show up as a nice spike in the frequency domain? Whereas I would expect uniform hashing to generate a flat, white-noise spectrum.
- edwintorok 13y agoI find the avalanche maps used here easier to grasp: http://home.comcast.net/~bretm/hash/5.html http://home.comcast.net/~bretm/hash/5.html Here is FNV, quite a lot of reds: http://home.comcast.net/~bretm/hash/6.html http://home.comcast.net/~bretm/hash/6.html And of course all green for SHA-1: http://home.comcast.net/~bretm/hash/9.html http://home.comcast.net/~bretm/hash/9.html
- anxrn 13y agoA Fourier transform is not merely another graphical representation of data (although, it could be used as such). Among other things, it lends itself to generating features and analysis that can be used for detecting patterns by computer, not just humans.
- dwc 13y agoHuman brains are quite good at spotting some kinds of patterns. A visual representation is a trivially easy way to access that pattern spotting ability. Trivial as in you can do it in the time it's taken me to write this reply. It also communicates well.