Hi all, I am trying to figure out 1) What to call my problem so I can better research the literature, and 2) see if anyone here knows of a solution. Essentially, I have a large set of f(x) vs x points (~20,000) which I need to split in to subdomains in x, and within each subdomain calculate a functional expansion of f(x). I want to do this in an optimal manner such that 1) the number of subdomains is minimized - or at least manageable, and 2) the number of expansion orders (probably Legendre) within each subdomain is also minimized. Does anyone have any idea what 'field' of math this could be considered, and where to begin searching around? Unfortunately, this is just a minor step in what I have to do so I don't want to expend much effort here. Thanks for your help!