For everyone having the same issue i found a bypass way. Although after i plot the data and when i zoom in i can see clearly the data is taken approximatelly, but that is not always the case, it depends. The idea is this: when you have done your smothing fitting curve just plot it, and then exract the data from x-axis and y-axis , like this:
fnplt(pp); %// the pp is an object and NOT vector or data
h = findobj(gca,'Type','line');
X_DATA=get(h,'Xdata'); %// the x-axis vector smoothed data
Y_DATA=get(h,'Ydata'); %// the y-axis vector smoothed data