CAS and evaluation of variables

[Bernd Grubert]

Hello,
I often do manipulation with expressions in CAS that contain variables that have assigned floating point numbers. When I carry out e.g. simplify the variable is replaced by the floating point number. This is an undesired behaviour (at least for me), since I'm interested in the symbolic result. If I needed the numerical value, I would have entered this expression directly in the HOME view.

It seems that putting the expression in quote disables the recursive evaluation, but this is uncomfortable and ackward to handle and the main purpose of the CAS should be symbolic calculation.

In my opinion this is quite easy to correct. One could disable the recursive evaluation by allowing the user to set the corresponding value to 0 in the corresponding CAS setting.

Another, in my opinion even better way, would be to modify the evaluation subroutine:
The subroutine could simply check whether the substitute is a numerical result or not. If it is numerical, it should keep the variable. The numerical evaluation could be called explicitly, e.g. by pressing shift ENTER.

Regards
Bernd