Rules of variables and functions declaring
The function name cannot be the same as the name of a previously declared variable, and vice versa, the name of a new variable should differ from the name of a previously declared function. This concerns built-in and user functions and variables.
Example:
The declared variable is the same as the name of a default function. Therefore, it cannot be accepted.
Example:
The declared function is the same as the name of the previously declared variable. The calculation performs in a fraction.
Remove the variable declaration. Put the cursor as shown in the figure above and press [Del].
After the variable deletion, the function x(y) and expression have recalculated. Now, it is properly calculated. We have a fraction expression result.