If you have any questions, please ask. I love yapping.

yapLet's say we have some periodic function f. The goal is to represent it as a bunch of sine waves. This is called a Fourier series (FS).

The FS coefficients are given by

            ⌠2⋅π
         1  ⎮         -i⋅k⋅x
f̂(k) =  ─── ⎮   f(x)⋅e       dx
        2⋅π ⌡0

for whole numbers k. We can then approximate the original function with

  n
 ___
 ╲          -i⋅k⋅x
 ╱    f̂(k)⋅e
 ‾‾‾
k = -n             

and make the approximation better by making n larger.

For non-periodic functions, we can still get an approximation! The Fourier Transform (FT) uses a continuous range of frequencies instead of whole numbers, and the sum is replaced by an integral (the inverse FT).

FT's are used everywhere, for example in signal processing and spectroscopy. If a recording contains an annoying high-pitched noise, we can apply the FT and filter the unwanted frequencies. Spectroscopy separates light into its different wavelengths. By comparing the resulting spectral lines with known measurements, we can determine which elements and molecules are present in stars and planets, for example.

idk what more to add ._.


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[–] 5 points 1 day ago (1 child)

I'm gonna go back to painting my nails again. I'm working with old folks so hoping it won't be much of an issue

I used to deliver food to the elderly and I was consistently surprised by how supportive and complimentary they were when I painted my nails. Like of any broad demographic I'd encounter, it was always the oldsters that went out of their way to say something positive. One of my very favorite clients to deliver to painted her nails the same color as mine one week and was super excited to show me, it was really sweet

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