I don't mean to shit on their interesting result, but exp or ln are not really that elementary themselves... it's still an interesting result, but there's a reason that all approximations are done using series of polynomials (taylor expansion).
> but there's a reason that all approximations are done using series of polynomials (taylor expansion).
"All" is a tall claim. Have a look at https://perso.ens-lyon.fr/jean-michel.muller/FP5.pdf for example. Jump to slide 18:
> Forget about Taylor series
> Taylor series are local best approximations: they cannot compete on a whole interval.
There is no need to worry about "sh-tt-ng" on their result when there is so much to learn about other approximation techniques.
Elementary function is a technical term that this paper uses correctly, not a generic prescription of simplicity.
See https://en.wikipedia.org/wiki/Elementary_function.