No natural exponential function and incorrect answers for approximation of `exp(x)`

[jackmaney]

Using 2.71828 as an approximation for e, we should have d/dx 2.71828^x close to 2.71828^x and S(2.71828^x dx)[0..1] should be close to e - 1. This is not even close to what happens:

Hi guys,thank you for using Hilbert.
You need to execute "postulate zfc_analysis" if you wanna do real analysis.

Enjoy! -> postulate zfc_analysis
success! :)
Enjoy! -> d/dx 2.71828^x
43.2( ( 8 ^ x )log( 8 ) )
Enjoy! -> S(2.71828^x dx)[0..1]
145.42366012
Enjoy! ->