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Toot

Written by erou ⏚ on 2025-01-21 at 14:35

I just learned about Briggs' algorithm to compute logarithms. It's a simple yet powerful idea: if you want to compute log(x) and you know a and b such that

log(a) ≤ log(x) ≤ log(b)

then you can compute the geometric mean

y = √ab

and you know that

log(y) = (log(a)+log(b))/2.

Then you proceed by dichotomy until you are satisfied with the precision you have.

It was used in 1624 (!!) to compute the logarithms from 1 to 20 000 and 90 000 to 100 000 with 10 digits of precision.

https://en.wikipedia.org/wiki/Henry_Briggs_(mathematician)

[#]math #maths

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Descendants

Written by fl on 2025-01-21 at 19:02

@erou C'est même ce phénomène qui est à l'origine des tables de logarithmes (voir 2:45 dans la vidéo de Benoît Rittaud.)

https://www.youtube.com/watch?v=-NcKh-qvb_g

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