[PD] Buffering numbers

[Sylvain]

Hi list,

I am encountering a problem that I had some time before under Max and I 
have the same now that I switched to Pd (actually it's more a logical 
one than a soft one)
Here it is : I am trying to retrieve the n last numbers of a float 
stream in order to sum them, and I want the n numbers to be refreshed 
every time a new value is coming (Like a hardware register does with bits)
I tried several methods with spigot, glue, lists ... but nothing works. 
Either I get all the values refreshed all at the same time (n times the 
current value) or I lost values on the way.
I also looked at data structures, it seems there is something to dig 
there but I am not familiar with data structures and I didn't succeed 
either.
If anyone has an idea, a tip or a clue, it would be very helpful.

To be more descriptive here is what I would like to see :

At time n :

inlet (float at t(n))
|
Logical function
|             |             |        
f(t(n)) f(t(n-1)) f(t(n-2)) ...

At time n+1 :

inlet (float at t(n+1))
|
Logical function
|             |             |        
f(t(n+1)) f(t(n)) f(t(n-1)) ...

n.b. : f is for float and not the function !!!! ;)
Of course, at initialisation only f(t(n)) would be non zero, but don't 
matter for now on.

Thx in advance

Sylvain