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Polynomial interpolation, smoothing, and differentiation.


yi = polyinterp(x,y,xi,width,order,deriv);


Estimates yi which is the smoothed values of y at the points in the vector x. (If the points are evenly spaced use the SAVGOL function instead.)


  • y = (M by N) matrix. Note that (y) is a matrix of ROW vectors to be smoothed.
  • x = (1 by N) corresponding axis vector at the points at which (y) is given.

Optional Inputs

  • xi = a vector of points to interpolate to.
  • width = specifies the number of points in the filter {default = 15}.
  • order = the order of the polynomial {default = 2}.
  • deriv = the derivative {default = 0}.


If y is a 5 by 100 matrix, x is a 1 by 100 vector, and xi is a 1 by 91 vector then:


gives the 5 by 91 matrix of first-derivative row vectors resulting from an 11-point cubic interpolation to the 91 points in xi.

See Also

baseline, lamsel, mscorr, savgol, stdfir