How to prevent automatic substitution during SIMPLIFY

[Luca]

I am new to the HP-50g, and I am noticing the following problem.
If I have an expression, say,

M * Q * (Q+1) * (Q-1) + 1

--------------------------

M + M * Q

and I hit SIMPLIFY, then the 50g tries to find definitions for M and Q, not only in the current directory, but (at least) in all the path from the current directory to the root. So if, say, one level above while working on something else I have variable M with value 0.3, when I click SIMPLIFY the value will be plugged into the expression, and the result will not be an expression in M and Q any more.
This is true also for EXPAND.
COLLECT works "correctly", just working on the equation at hand.

Is this the intended behavior?
How can I prevent variable expansion from taking place? I would simply like to be able to work on an expression, regardless of what variables I might have defined at an upper level (or at the same level).

I am using the latest ROM, C-2.15, if this makes a difference.
Many thanks!

Luca

[Jonathan Eisch]

Hello Luca,

Many of the users of this forum primarily use the older HP calculators. The hp-50g is based on the hp-48 series of calculators, and you will probably have better luck finding your answers on a list devoted to those, such as the comp.sys.hp48 newsgroup (easily accessible using google groups). I'd suggest using the search function, as that list has probably answered similar questions from someone in a position similar to yourself.

You can also find most of your answers in the Users Guide or the HP 50g Advanced User's Reference Manual.

Generally speaking, the answer to "Is this the intended behavior?" is "yes" as the ROMs are very mature.

-Jonathan

(edit: forgot to sign my name)

Edited: 16 Aug 2009, 9:51 p.m.

[Luca]

Thanks, I will follow this advice.
I also usually use older calculators (the 32SII is my favorite, due to speed of operation, followed by the 42S); I got a 50g for its CAS abilities -- but I have difficulties making it work as I like.

Best, Luca.