Question

How do I write a periodic extension of a function?

Answer 1

Like a cosine extension?

Answer 2

Or a fourier extension?

Answer 3

I wrote a function that ends, and I want it to repeat forever.

Answer 4

sen (x), cosine (x) are like that

Answer 5

The graph I have is piecewise. I used unit step function.

Answer 6

Fourier extension

Answer 7

So you need to map it to a fourier basis by taking the inner product of your function and the sin(x) cos(x) and 1 functions.