Approximation theory/Proofs
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Proof
Approximation theory
Proof that an Nth degree polynomial that gives rise to an error function that has N+2 maxima, of alternating signs and equal magnitutes, is optimal.
This is most easily seen with a graph. Let N=4 in the example. Suppose P(x) is an Nth degree polynomial that is optimal, and that P(x)-f(x) oscillates among N+2 maxima.