PLS_Toolbox Documentation: savgol	< rwb	savgolcv >

savgol

Purpose

Savitsky-Golay smoothing and differentiation.

Synopsis

[y_hat,cm] = savgol(y,width,order,deriv)

Description

SAVGOL performs Savitsky-Golay smoothing on a matrix of row vectors y. At each increment (column) a polynomial of order order is fitted to the number of points width surrounding the increment. An estimate for the value of the function (deriv = 0) or derivative of the function (deriv > 0) at the increment is calulated from the fit resulting in a smoothed function y_hat.

[y_hat,cm] = savgol(y,width,order,deriv) allows the user to select the number of points in the filter width {default = 15}, the order of the polynomial to fit to the points order {default = 2}, and the order of the derivative deriv {default = 0}.

Output cm allows the user to apply smoothing to additional matrices of the same size as y, e.g. y_hat2 = y2*cm where y2 is the same size as y used to determine cm.

Note: width must be ≥ 3 and odd, and and deriv must be ≤ order.

Examples

If y is 3 by 100 then

y_hat = savgol(y,11,4,2);

yields a 3 by 100 matrix y_hat that contains row vectors of the second derivative of rows of y resulting from an 11-point quartic Savitzky-Golay  smooth of each row of y.

See Also

baseline, baselinew, deresolv, lamsel, mscorr, polyinterp, savgolcv, stdfir, wlsbaseline