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CAS Settings: disable predefined variables option?
12-15-2020, 01:08 PM (This post was last modified: 12-15-2020 01:17 PM by ramon_ea1gth.)
Post: #1
CAS Settings: disable predefined variables option?
I would like to propose this setting option in the CAS Settings: to disable the predefined variables only for the CAS. Of course, I do not know the implications in the software implementation, so the trade-offs are in the hands of the developers. But I would find this option extremely useful, and fortunately, the HP Prime has two separate environments (HOME/CAS) that I guess, would allow this.

On the one hand, predefined variables are fine in HOME, and specific variables for a certain application can be added when creating a custom application. So I like the way you can prepare a sandboxed app, sharing some global predefined variables for common tasks like graphing.

On the other hand, I find this behaviour less practical when using the CAS, e.g., to analyse Electrical Engineering expressions, performing symbolic operations or simplifications (numeric calculations are not the goal). The CAS speed is awesome, so this is really practical, and the details of the simplifications can be truly rich: I like it.

However, the kind of expressions I enter in the CAS usually carry names like I (electrical current), V (voltage), R (resistance), L (inductance), C (capacitance), Z or Z0 (impedance), E (electric field), B or H (magnetic field) or spherical coordinates with the standard names r, θ, φ. These expressions can be differentiated, integrated or organised in differential equations, and usually trigonometric functions and complex numbers are involved.

From the names above, it can be seen that most of them match the names of the predefined global variables. The recommended workaround has been to avoid capitalisation in the CAS or use two letters. However, for some formulas this leads to non-standard notations, cumbersome translations of parameters and when in a classroom, incongruence between the expressions explained on the blackboard and the displayed formulas in the calculator.

The HP Prime is wonderfully rich in scientific characters. And the possibility of applying this setting in the CAS would be something great from my point of view. How do you feel about this?


Valladolid, Spain
TI-50, Casio fx-180P, HP48GX, HP50g, HP Prime G2
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