Bug: HP Prime can't do Log's

[Tim Wessman]

Quote:However, aside from the fact that the HP Prime doesn't solve quadratics as easily as the TI-84

You have two ways to solve this immediately that come to mind. First, use the CAS solve command.

1. Press CAS.
2. Toolbox->CAS->solve->solve (CAS button is at the bottom of the screen)
3. Type your equation, followed by =0,x (giving something like solve(x^2+3*x-3=0,x) )
4. Press ENTER. See something like {1/2*(-sqrt(21)-3),1/2*(sqrt(21)-3)}

The "proot" command already mentioned. This can be found in the toolbox->CAS->Polynomial->Find Roots entry.

(12-14-2015 04:26 AM)davimle Wrote:  However, since fewer digits are shown, this just seems to be a case of rounding. (e.g. with the first one, doing ANS - 4 returns -1.00000000E-11 just as one would expect.) So this doesn't feel like the a real solution.

Actually, you've hit EXACTLY on the solution the other calculators are using! All other manufacturers do an internal fudging on the display using "guard digits". These are extra numbers at the end are not shown to the user and are used to accumulate the error in a non visible spot (the display is rounded to remove them when shown to the user).

Try this fun thing and you'll see what I mean. On the other units do a 1/3 and evaluate. Now, multiply that by 3 again doing Ans*3 in a second step. You will get 1. Now do it again, but this type don't use the Ans*3, but rather type the number you see shown to you. (.3333333333...) with the exact number of 3s and multiply by 3. This time, you'll end up with .999... instead.

To make Prime behave most closely here to the TIs, you want to turn on the "Rounded" display option. The "standard" that is default on Prime is the exact same behavior and default on your old 28s units you used in college.

Quote:and did HP seem to understand the gravity of the situation?

Yes, we did understand and correct it in the source. When/if there is an update it will be included.