Associative array / dictionary / hash / map

[parisse]

Open Settings, select algebraic entry, after that you can do:
t["one"]:=1;
t["two"]:=2;
If t is a table, t[index] will return the value stored, or 0 if nothing is stored. The idea is to store sparse matrices with these kinds of objects for efficiency:
t:=convert(identity(3),table);
t*t;
t+t;