Yeah, wiki has a decent survey of sigmoid (the family, not the specific function ML people often refer to by that name) functions here: https://en.wikipedia.org

Yeah, wiki has a decent survey of sigmoid (the family, not the specific function ML people often refer to by that name) functions here: https://en.wikipedia.org/wiki/Sigmoid_function#/media/File:Gjl-t(x).svg https://en.wikipedia.org/wiki/Sigmoid_function#/media/File:G... Note that tanh saturates to ±1 faster than most except erf when normalized to have slope 1 at the origin (its series at +infinity is like 1 - 2e^{-2x} + o(e^{-4x}), while many of the other options have polynomial series, so they don't approach 1 nearly as fast). I suspect some applications would in theory rather use erf, but erf is even worse to compute than tanh (on the other hand, erf's derivative is really nice, so who knows?)