Still doesn’t work. If (xi)3i=1 is an arithmetic progression then (exp(i(axi+b)))3i=1 is a geometric progression, the imaginary part of which is (sin(axi+b))3i=1. This implies that for example sin(ax+b) cannot simultaneously approximate (0,0), (1,0), and (2,1).
Sorry, we need sin(ax + b).
Still doesn’t work. If (xi)3i=1 is an arithmetic progression then (exp(i(axi+b)))3i=1 is a geometric progression, the imaginary part of which is (sin(axi+b))3i=1. This implies that for example sin(ax+b) cannot simultaneously approximate (0,0), (1,0), and (2,1).