www.gusucode.com > matlab 案例源码 matlab代码程序 > matlab/FitPolynomialToSetOfPointsExample.m
%% Fit Polynomial to Set of Points % %% % Create a vector of 5 equally spaced points in the interval |[0,1]|, and % evaluate $y(x) = (1+x)^{-1}$ at those points. % Copyright 2015 The MathWorks, Inc. x = linspace(0,1,5); y = 1./(1+x); %% % Fit a polynomial of degree 4 to the 5 points. In general, for |n| points, % you can fit a polynomial of degree |n-1| to exactly pass through the % points. p = polyfit(x,y,4); %% % Evaluate the original function and the polynomial fit on a finer grid of % points between 0 and 2. x1 = linspace(0,2); y1 = 1./(1+x1); f1 = polyval(p,x1); %% % Plot the function values and the polynomial fit in the wider interval % |[0,2]|, with the points used to obtain the polynomial fit highlighted as % circles. The polynomial fit is good in the original |[0,1]| interval, but % quickly diverges from the fitted function outside of that interval. figure plot(x,y,'o') hold on plot(x1,y1) plot(x1,f1,'r--') legend('y','y1','f1')