Oh OK, thanks yes that's what I was looking for!
However if this NN can represent non Periodic functions, what cost does the Periodic function support incur on non Periodic function accuracy, if any?
It actually behaves a lot better than non periodic functions in some scenarios.
It seems that period functions enable a network to encode positional information within [-1,1]. This is supported by the fact that positional encoding is needed in transformers to make them work.