Torture tests: what do they mean?

[HP67]

(05-15-2014 06:01 PM)jebem Wrote:  Test 1:
(sqrt(6)^2)-6
So, the expected precise result should be Zero, right?

As DavidM pointed out, in CAS (exact mode) you get 0.

(05-15-2014 06:01 PM)jebem Wrote:  Test 2:
(10^15 + 7.2 − 10^15) * 100
The expected result should be 720.

And you can get that on the HP 50g also, but it's not exactly obvious how to do it.

DavidM pointed out the difference in approximate and exact mode. He also noted the decimal value 7.2 causes the expression to be evaluated in approximate mode.

If you key that expression in on the 50g and use the down arrow to pull up the expression in the Equation Writer, use SIMP to simplify the expression according to the rules of algebra and you get 720

(05-15-2014 06:01 PM)jebem Wrote:  I see a similar behavior between the Prime and the 50G in so many situations that I guess HP have just ported the 50G algorithms. That would explain the apparent lack of precision for such a modern and powerful hardware sported on the Prime.

HP has a long history of intentionally using the same (good) algorithms. If not, there would be a lot of unhappy customers. Once you learn something it's good if the next generation is evolutionary, not revolutionary. As someone who works on software with a long lifetime, I agree with this approach.

As you pointed out, science is harder than technology and doesn't go at the same pace. Is it really so bad if the Prime didn't rock the world with new algorithms?