We'll work it out in another world.
https://gyazo.com/c70f77e7a0de96919aa9ac7ab4b122bb
What is difficult to do in the present world is accomplished by projecting it into another world, doing it there, and then returning to it.
Rotation is unwieldy in the Cartesian coordinate system, so it is converted to the polar coordinate system, rotated there, and then returned to the original coordinate system.
Fourier analysis can transform time series data (data in the time domain) into the frequency domain. For example, convolutional integration is simply multiplication in the frequency domain.
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