log operates on any input, yes even negative ones. the manual admits that the sign is ignored for both logs and square roots. e^x only accepts arguments within +/-10. this must be down to the internal algorithm because e^x of bigger numbers could be displayed. notice that there is no Exp button. there is no way to supply an exponent and no exponential values are displayed. anything bigger than the 8 digits is overflow.
i discovered a fascinating secret fact with the tan function for values near 90 degrees. this was during my attempt at tan 355/226 radians as part of the torture test. interestingly values near enough to 90 degrees that cause the result to exceed 1000 are rejected as overflow (ie reported as an error). this means the closest value to 90 that tan accepts is arctan(1000) = 89.9427 and tan(89.9427) is reported as 999.93. the range exclusion around 90 is not documented but what is interesting is that the engineers knew that the results were somewhat wrong near 90 and decided to exclude this range rather than display the wrong answer. this is commendable because giving out bogus answers is bad form. it must work by performing the internal algorithm then testing against 1000 and rejecting afterwards.
something else i didnt mention that you cant see here, is the most splendid way the display flickers and dances whilst the calculations are in progress. some take a few seconds (none as long as the fx-1 which takes 16 seconds for cube root, then again this model does not have that one).