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amavecttoday at 3:58 PM1 replyview on HN

>You might ask: if we have a baseless logarithm log(N), do we also have a “baseless exponential”?

Sure we can, with some naive algebra. If we can take log(x,base) and drop the base, then we can also take pow(base,x) and drop the base. Since bits=log(2), then pow(bits)=2. You can probably connect it to the reverse of things, like integrals.

Also, for fun, I'll play with some notation tricks.

  log(freq) = pitch
  freq = pow(pitch)
  octave = log(2)

  400*Hz = 100*Hz*4  // the frequency 400 Hz equals 4 times 100 Hz
  log(400*Hz) = log(100*Hz) + log(4)
  log(400*Hz) = log(100*Hz) + 2*log(2)
  log(400*Hz) = log(100*Hz) + 2*octave
  log(400*Hz) = log(100*Hz) + 2*octave  // the pitch of 400 Hz equals 2 octaves above the pitch of 100 Hz

  cent = log(2)/1200
  A4 = log(440*Hz)
  B4 = A4 + 200*cent  // the pitch B4 equals 200 cents above A4
  B4 = log(440*Hz) + 200*log(2)/1200
  B4 = log(440*Hz) + log(2^(2/12))
  B4 = log(440*Hz * 2^(2/12))
  pow(B4) = 493.883 Hz  // the frequency of B4 equals 493.883 Hz
I like the intuition that baseless logarithm notation gives, and it also avoids needing to choose a specific reference point. I can also directly calculate by choosing an arbitrary base:

  pow(log(440*Hz) + 200*log(2)/1200)
  exp(ln(440) + 200*ln(2)/1200)

Replies

ajkjktoday at 5:40 PM

True, I guess you can just 'curry' exponentiation and say that's a baseless power. I couldn't find a clean notation for it so I gave up..