01-28-2014 07:23 PM
I use 'undo' on my HP-50g often for a mistaken operation on my RPN stack.
I have not seen this ability really on the Prime. Sure I could just press the reset button and let the reboot put me back where I was (assuming that was right after I powered up). Not a 'pure' method.
Also, when I'm editing a note, spreadsheet, etc., I run into the same problem -- oops, I didn't mean to delete all that, where is the control-Z key?
If there is not an undo on the Prime, it is yet another one of my suggestions.
03-05-2014 07:24 PM
No one in english has answered this post.. even "auf deutsch" there is a lot of answers, why not in english...Take a look at:
03-07-2014 08:48 AM
I know that the "UNDO" key is already imposible to implement from the actual phisical achitecture of the HP Prime, but how about on the next "HP Prime II"? please don't forget about this missing key!
10-15-2014 03:31 PM
As a suggestion : there is an app for iPhone ( Pcalc42 ) where to undo , simply slide your finger up the screen to the left , and redo , slides to the right.
It would be fantastic in the HP Prime!
10-16-2014 09:22 AM
Don't forget about [Shift] [+] which sort of "undoes" the most recent RPN calculation, by pushing its arguments onto the stack. It's the same as LASTARG on the RPL models (HP 28/48/49/50). Ignore the fact that it's labeled "Ans" on the keyboard. In does NOT return the most recent Answer; it returns the most recent INPUTS to a function.
Example: 1 Enter 2 + Ans --> 3, 1, 2 on the stack (the result and the inputs).
This is very handy, and not only when you want to UNDO an operation. For example, what's the resistance of a 6 ohm and 10 ohm resistor connected in parallel? The usual way to calculate this is 1/(1/A+1/B) which in Prime RPN can be done this way:
6 [X^-1] 10 [X^-1] [+] [X^-1] --> 3.75 ohms
But it's also equal to (A*B)/(A+B) which in Prime RPN can be done this way:
6 10 [×] [Ans] [+] [÷] --> 3.75 ohms