TI Nspire CX ii

[Wes Loewer]

(04-22-2020 04:54 PM)lrdheat Wrote:  I had not been aware of non CAS calculators that could do triple integrals!

I think the non-CAS hp 48 could do nested integrals back in the 90's.

As far as the TI Nspire CX II (non CAS) calculator goes, I suspect it sometimes uses a CAS under the hood, but keeps it hidden from the user. For instance:

On the numeric TI-84+, d/dx (abs(x),x)|x=0 incorrectly returns 0 which makes sense since the calculator is using (f(x+epsillon)-f(x-epsillon)) / (2epsillon) where epsillon=0.001 .

However, the non-CAS Npsire correctly returns "undefined". How would it know that this was undefined unless it did some sort of CAS operation? Or maybe I'm just not thinking about this correctly. (It's been known to happen.)