First extend from n-dimensional vector space to Hilbert (infinite) vector space
Then introduced by Hilbert into the function space
Then consider the Fourier series from the function space and basis
and introduces the basis of other function spaces ♂
These articles give us new ideas: these things can be considered in terms of linear transformations.
Understanding of the orthogonalization process: It has always been a dead formula before. . .
First select the first vector a, and then subtract its projection <a,b>/<a,a> on the first vector for the second vector b. The ab inner product is divided by the length of a
Fourier series: for periodic functions
Fourier transform: Period -> ∞ is the generalization of Fourier.
Inner product: the product of a vector projected onto another vector and another vector
Very good introduction to Fourier analysis website! ! !
Know about the progressive explanation of Fourier's layers! ! very nice