Polynomial Curve Fitting
polyfit finds the coefficients
of a polynomial that fits a set of data in a least-squares sense:
p = polyfit(x,y,n)
x and y are vectors containing
the x and y data to be fitted,
and n is the degree of the polynomial to return.
For example, consider the x-y test data
x = [1 2 3 4 5]; y = [5.5 43.1 128 290.7 498.4];
A third degree polynomial that approximately fits the data is
p = polyfit(x,y,3)
p =
-0.1917 31.5821 -60.3262 35.3400
Compute the values of the polyfit estimate
over a finer range, and plot the estimate over the real data values
for comparison:
x2 = 1:.1:5;
y2 = polyval(p,x2);
plot(x,y,'o',x2,y2)
grid on
Note
Least squares fitting of data is treated in the Data
Analysis section of the MATLAB documentation. |
 | Partial Fraction Expansions | | Characteristic Polynomials |  |
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