HP 50G help

[Tugdual]

(04-24-2015 07:34 PM)DavidM Wrote:  

(04-24-2015 05:19 PM)Tugdual Wrote:  It is indeed something fundamental to understand.
But this being said is that the right way to go? The calculator would naturally feed the root directory with a lot of crap and a purge is tedious; my conception of a directory is precisely to isolate/encapsulate problems in their own context. So when I create a subdir I would expect to start with a blank page.
In my humble opinion, this mechanism totally ruin the concept of directories.

As others are pointing out, there's benefits to this technique and at the same time you can still be more explicit with your own programs if needed.

Note that this is more of an issue for RCL than STO. Consider the following:

- you have an object named 'ABC' in HOME containing the string "ABCDEFGHIJK"
- your current directory is set to { HOME MyVars MyStrings }, and it contains no objects

In this scenario, if you place 'ABC' on the stack and execute RCL, you will end up with "ABCDEFGHIJK" on the stack that was recalled from HOME. Conversely, if you enter "XYZ" and 'ABC' on the stack and press STO, the result will be two different 'ABC' variables in two different locations: { HOME } and { HOME MyVars MyStrings } . The original version in HOME is left unchanged, and a new one is stored in the current directory.

Understood, but root variables are pretty similar to global variables which I tend to avoid since the day I started OOP.

Also the major drawback is that you cannot undefine a variable locally, hence CAS will be confused and would use root variable when you really meant it to be unknown and symbolic. I can't help finding that very misleading.

Finally the VAR button does only show variables of the current directory while there could be much more available at this stage. This I think is the origin of my confusion and somehow this is not consistent with the way the calculator actually operates.

This being said I respect all opinions expressed from people having obviously much more experience than I on this topic. I'll obviously need to dig a little bit more in the user guides. Tx all for feedback.