MATLAB® and Its Applications in Engineering: [Based on MATLAB 7.5 (R2007b)]

4.12. Polynomial Curve Fitting

In case a set of points is known in terms of vectors x and y, then a polynomial can be formed that fits the given points. The following command is used for this purpose:

c = polyfit(x, y, k)

where

x and y specify the vectors of the points for curve fitting, and

k specifies the order of the desired polynomial.

The command returns the coefficients of kth order polynomial that fits the data in descending powers of x, in a least-square sense.

Example 4.18.

Find a polynomial of degree 2 to fit the following data: x 0 1 2 4 y 1 6 20 100 Solution: x and y are represented by the following row vectors: x = [0 1 2 4]; y = [1 6 20 100]; To find a polynomial of degree 2 to fit the data given by x and y, the command is c = polyfit(x, ...