hi jgcode,  
thanks for your reply. 
i tryied your solution but i couldn't managed it. (   The next step is to build a circular buffer" i couldn't understand, what does it means "circular buffer"?? :s   ) 
after i tryied other solution and i saw signals.  
the last problem about program,  
The program can't save the "coefficent" and "plus" number. can i save this number. i don't want to write it everytime when  i open the program  
i hope i'll solve that problem. 
again, thanks for everything... 
hakan...