The Even-length Savitzky-Golay Filter

The even-length Savitzky-Golay filter with a Gram polynomial approach.

The even-length Savitzky-Golay filter (i.e., polynomial filter or least-squares filter) for data smoothing and differentiation.

The filter coefficients are calculated with the recursive properties of Gram polynomials so as to avoid the inaccuracy in a matrix approach (http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=4038&objectType=file) due to ill-conditioned matrix.