citation missing?

[javiribera]

The README says that the centers and radius are taken as follows:

centers are taken uniformly from the bounding hyperrectangle of the inputs, and
radius = max(||x-c||)/sqrt(n_centers*2)

but citation [2] only talks about ELM, and [3] talks about RBF, but the centers and radius are taken in a different way. Is the solution in this implementation an idea of @dclambert or is there a citation missing?

[dclambert]

There is a citation missing. Unfortunately I’m not sure where I got this anymore.

[javiribera]

It seems a pretty critical issue to describe why this implementation uses this particular model. Also none of those two papers seem to describe why the activations from both ELM-RBF and ELM-MLP are summed (https://github.com/dclambert/Python-ELM/blob/master/elm.py#L357). It may be useful to set alpha to 0 or 1 to select between both, but a weighted average seems unfounded without justification.