(sum_i ai x^i)(sum_j bj x^j) when you expand that, the coefficient of x^k is the... | Hacker News

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		sriku on Nov 24, 2020 \| parent \| context \| favorite \| on: Convolution Is Fancy Multiplication (sum_i ai x^i)(sum_j bj x^j) when you expand that, the coefficient of x^k is the sum of aibj such that i+j=k which is discrete convolution. Set x=10 and you're dealing with decimal representation of numbers.

rualca on Nov 25, 2020 [–]

> Set x=10 and (...)

...and you no longer have a function, only the image of a function at a specific point of its domain.

Convolutions are functions, not functions evaluated at a specific, and cherry-picked point.

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