Quote1) preprocessing can even be done with pen and paper, it not preprocessing that is done during e.g. a library init, ..but preprocessing before you begin with coding. Is about estimating constants.Indeed, as with R22, R33 etc.But it ain't always necessarily so in software.Quote2) We get a polynomial (or Padé or something else) approximation of exp in some interval. Inside that interval is will have limited error and predictable behaviour. Outside the interval, we will use the "rescale K" trick to translate it back inside the interval. So robustness is not an issue (if you only work inside a fixed, calibrated/optimized interval), right? Limited error and predictable behaviour, yes; except for the pathological cases.