% Sine series for f(x)=x*(1-x) on [0,1]
n=input('Choose n');
clear c;
for j=1:n
    c(j)=4*(1+(-1)^(j+1))/((j^3)*(pi^3));
end;
xgrid=0:0.01:1;
hold off
fn=zeros(size(xgrid));
for j=1:n
    fn=fn+ c(j)*sin(j*pi*xgrid);
end
plot(xgrid, xgrid.*(1-xgrid), xgrid, fn);