Savitzky-Golay Smoothing Filter

Very simple function for Savitzky-Golay Smoothing

After looking at a lot of the Savitzky-Golay implementations on File Exchange, I could not find one as simple but as effective as this one. savGol is from the Book, "Solving Problems in Scientific Computing Using Maple and Matlab" by Walter Gander and others. Gander cites Teukolsky from Computers in Physics from 1990. Here is a link to the book website:
http://www.solvingproblems.ethz.ch/
g = savGol(f, nl, nr, M)

f: noisy data

nl: number of points to left of reference point

nr: number of points to right of reference point

M: Order of least squares polynomial

Example:
x = [0:1000-1]'/(1000-1);
signal = exp (- 100*(x - 1/5).^2) + exp (- 500*(x - 2/5).^2) + exp (-2500*(x - 3/5).^2) + exp (-12500*(x - 4/5).^2);
randn ('seed', 0);
noisySignal = signal + 0.1* randn (size (x));

smoothSignal = savGol(noisySignal, 16, 16, 4);

plot(x,noisySignal)
hold on;
plot(x, smoothSignal,'r','LineWidth',3)
legend('Noisy Signal', 'Smooth Signal')