Answered
Let list1 = {1,2,3} be a list with 3 elements.
In Algebra view: Element[list1,4] is undefined - OK
but
in CAS view: Element[list1,4] = 0 ???
Even Element[list1,-2] = 2 is possible but non meaningful.
ggb 4.2.30
Andreas
Files:
Liste_Index.png
The same problem 
hi
in effect Element[list1,-2] = 2 is a way to define a list; but , in classic objects libraries, you can define default value;
so you can control the list behavior
i.e.
list1.default := undefined;
element(list1,2):= 2
element(list1,4):=5
so list is { .., undefined, undefined, 2, undefined, 5, undefined, ... }
Comments have been locked on this page!