My problem is not serious,
its just a question about the most beautifull solution.
Maybe somebody has a better idea!
I have a mathematical class having some numerical functions.
It is convenient for me, and speed up the program,
if I introduce a member array called "memory",
and store the values of the previous calling.
(for example Maple can do the same)
Before this solution my function has the const qualifier,
but now it cannot be const, because I write in the memory.
Its ok for a programmer,
but its not logical to a mathematician,
since I only get values with the calling of that function.
If I use my class as a member in another class,
I cannot call the non const function from another const function,
which is inconvenient also.
An other solution is to use global memory variables,
but I have not just one object from the same class,
so I cannot use the same global variable.
Therefore this solution is dirty also. Any idea? Thanks