Polyinterp
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Purpose
Polynomial interpolation, smoothing, and differentiation.
Synopsis
- yi = polyinterp(x,y,xi,width,order,deriv);
Description
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.) INPUTS:
- 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}.
Examples
If y is a 5 by 100 matrix, x is a 1 by 100 vector, and xi is a 1 by 91 vector then polyinterp(x,y,xi,11,3,1) gives the 5 by 91 matrix of first-derivative row vectors resulting from an 11-point cubic interpolation to the 91 points in xi.