HP 10bii+ Margin/Markup bug

[Rick314]

(03-29-2021 01:08 AM)Gamo Wrote:  This can be done on the HP-12C ...

Gamo: Sorry, but what you demonstrated does not solve the proposed problem. Maybe that problem isn't clear.

Quote:On any HP calculator, a Solver function (so limited to that tool) that solves all markup, cost, price, margin (MU CST PRC MAR) problems, finding all possible solution variables by solving for any possible solution variable.

This is a user interface problem, not a problem with making a programming language do the required mathematics using additional keys and keystrokes.

The main point of the thread is that HP firmware engineers could have made the MU CST PRC MAR keys on the HP 10bII+ (and other calculators) work as users expect instead of giving errors for valid input-output cases. Specifically, once the 4 variables involved are cleared to zero, these 12 keystroke sequences must work (plus entering the inputs in any order).

Code:

#   Keystrokes        Solves For
==  ================  ==============
01  20 MAR MU         MU
02  20 MAR 4 CST MU   MU, PRC
03  20 MAR 5 PRC MU   MU, CST
04  4 CST 5 PRC MU    MU, MAR
05  25 MU MAR         MAR
06  25 MU 4 CST MAR   MAR, PRC
07  25 MU 5 PRC MAR   MAR, CST
08  4 CST 5 PRC MAR   MAR, MU
09  5 PRC 25 MU CST   CST, MAR
10  5 PRC 20 MAR CST  CST, MU
11  4 CST 25 MU PRC   PRC, MAR
12  4 CST 20 MAR PRC  PRC, MU

That is what the provided HP 200 LX solution does, and all Solves For values are visible immediately after the last keystroke. If implemented on a calculator with a 1-line display (like the HP 10bII+ or 12C or 42 or ...) then doing the additional keystrokes "RCL <second Solved For variable>" would also be allowed. But that's it. No use of any additional keys or keystrokes.

4/9/21 error correction: "02 20 MAR 4 CST MU -> MU, PRC" (corrected) was "02 25 MU MAR -> MAR" (error, duplicate of row 05).