R=0.1;
t1=2;
ts=t1/4;
df=1/(15*ts);
f=0:df:2/ts;
for  i=1:length(f)
if f(i)<(0.5*(1-R)/ts)
    Xf(i,:)=ts;
else if f(i)>(0.5*(1+R)/ts)
        Xf(i,:)=0;
    else
        Xf(i,:)=0.5*ts*(1+cos((pi*ts/R)*(f(i)-(1-R)*0.5/ts)));
    end
end
end
figure(1)
stem(Xf);
xt=ifft(Xf);
figure(2)
stem(xt);
xt1=xt(1:16);
figure(3)
stem(xt1);