How to filter a signal..plz help me..

Hi all, I have a question and I need your help.. I make a file that:

%----------------------------------------------------------
fs = 100;
t = 0:1/fs:1;
x = sin(2*pi*t*3)+.25*sin(2*pi*t*40);
b = ones(1,10)/10;             % 10 point averaging filter
y = filtfilt(b,1,x);           % Noncausal filtering
yy = filter(b,1,x);            % Normal filtering
plot(t,x,t,y,'--',t,yy,':')
%-----------------------------------------------------------

It will be Ok if "fs" is 100.When "fs" is 10000.It isn't smooth with "y" and "yy"...What do I have to do? Plz help me... thank all..

[Jan]

What do you have to do to achieve what?

You have examined the behaviour of two filter methods to two different signals and see a difference. But how could we suggest a change without knowing, what you want to change? Where is the problem?