0
votes
0answers
104 views

What is the difference between multiplying two functions and sum their product over $x$?

I am studying wavelets and I found this equation in the DWT section: $$W\varphi(j_0,k)= \frac{1}{M}\sum_x \left(f(x) \varphi(j_0,k)(x)\right)$$ I am wondering which is the difference with this: ...