Can functions be approximated with series other than Taylor and Fourier?

[gulsen]

I wonder if there's any other series that can be used to approximate a function, other that Taylor/McLaurin and Fourier. For instance, can we expand a function in terms of Gaussians (Aexp(-bx^2))? Maybe something else?

 

[daveb]

From what I remember of functional analysis (it was a while ago), as long as the individual functions in the series form a basis for the function space, then yes, you can expand it in terms of that series. For example, the sine/cosine functions form a basis and are used in Fourier expansions.