Algorithm for entering numbers?

[Ángel Martin]

(08-12-2019 08:08 AM)grsbanks Wrote:  

(08-12-2019 05:36 AM)Ángel Martin Wrote:  For example, RC+ nn is equivalent to { RCL nn, followed by + } and logically the Rnn value becomes the new "x" before the addition.

My take is that the value in Rnn is still preserved in Rnn after the operation while the value in X that it is added to is lost. The stack can therefore be reconstructed in its original form with [CLX] [LASTX] if the initial value of X is what is saved in LASTx.

Interesting view, somehow it reinforces the notion that "LastX" is whatever was last in x before executing the function, regardless of wthat might be (even bringing other values from memory on-the-fly). But I still don't like that, I guess I value more the consistency with the two-step approach ( RC+ = RCL , + ) just to be on the safe side.

BTW I did a check on Free42 and it appears to follow your option, so you're in good company as supposedly that's also how HP did it on the original HP-42S, is it correct?
And on the DM-42 by extension it should also behave the same way... does it?

(08-12-2019 08:08 AM)grsbanks Wrote:  Of course, the same could be achieved by following up with RC- nn but you might lose some precision depending on the difference between Rnn's and X's exponents.

True as well, something more to consider...