Calculators and numerical differentiation

[Wes Loewer]

Instead of averaging the backwards and forwards differences, why not just check to see if f(a) exists and if it does then do the central difference method?

Notice in the TI manual that the default epsilon can be overridden. Same goes the their 8x numeric models.

The non-CAS Nspire apparently has a bit of CAS hidden under the hood because it does not use this approximation. It appears to evaluate the derivative symbolically and then evaluates that expression numerically, keeping the CAS carefully hidden from the user.

(Had anyone previously seen the del operator used for the backwards difference as shown in the Casio manual?)