The Legendre symbol is notation for whether a quadratic equation has a solution modulo a prime. What does this have to do with Ethereum proof of custody?

John D. Cook Consulting Blog

27.06.2025

Test whether an arbitrarily large integer is a square

A short and sweet bit of Python code to test whether an arbitrarily large integer is a square, and to find the floor of the square root.

John D. Cook Consulting Blog

28.06.2025

Most machine integers are not machine floats

Most numbers that are representable as machine integers are not exactly representable as floating point numbers.

John D. Cook Consulting Blog

29.06.2025

Zooming in on a fractalish plot

The exponential sum of the day page on my site draws an image every day by plugging the month, day, and year into a formula. Details here. Today's image looks almost solid blue in the middle. The default plotting line width works well for most days. For example, see what the sum of the day

home›John D. Cook Consulting Blog

John D. Cook Consulting Blog

Science

Legendre PRF and Ethereum 2.0 Proof of Custody

Test whether an arbitrarily large integer is a square

Most machine integers are not machine floats

Zooming in on a fractalish plot

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John D. Cook Consulting Blog