User`s guide

smooth
4-131
The first four elements of yy are given by
yy(1) = y(1)
yy(2) = (y(1)+y(2)+y(3))/3
yy(3) = (y(1)+y(2)+y(3)+y(4)+y(5))/5
yy(4) = (y(2)+y(3)+y(4)+y(5)+y(6))/5
Because of the way that the end points are treated, the result shown above
differs from the result returned by the
filter function described in “Difference
Equations and Filtering” in the MATLAB documentation.
In this example, generate random data between 0 and 15, create a sine wave
with noise, and add two outliers with the value 3.
rand('state',2);
x = 15*rand(150,1);
y = sin(x) + (rand(size(x))-0.5)*0.5;
y(ceil(length(x)*rand(2,1))) = 3;
Smooth the data using the loess and rloess methods with the span specified
as 10% of the data.
yy1 = smooth(x,y,0.1,'loess');
yy2 = smooth(x,y,0.1,'rloess');
Plot original data and the smoothed data.
[xx,ind] = sort(x);
subplot(2,1,1)
plot(xx,y(ind),'r.',xx,yy1(ind),'k-')
set(gca,'YLim',[-1.5 3.5])
legend('Original Data','Smoothed Data Using ''loess''',2)
subplot(2,1,2)
plot(xx,y(ind),'r.',xx,yy2(ind),'k-')
set(gca,'YLim',[-1.5 3.5])
legend('Original Data','Smoothed Data Using ''rloess''',2)