precalculus does matter

I just spent three days working out why two different language modeling schemes were producing vastly different log-probabilities. I was using every bit of good software design practice that I know, and leaning on colleagues to confirm that I was running it right.

You know why it all went wrong? System X produces probabilities in logarithms of base 10, and system Y does it in base e.

This reminds me of the stories about the Mars Climate Orbiter unit conversion error, although that is apparently apocryphal.