www.gusucode.com > curvefit 案例源码程序 matlab代码 > curvefit/CreateFitOptionsandFitTypeBeforeFittingExample.m
%% Create Fit Options and Fit Type Before Fitting % Load and plot the data, create fit options and fit type using the |fittype| % and |fitoptions| functions, then create and plot the fit. % Copyright 2015 The MathWorks, Inc. %% % Load and plot the data in |census.mat|. load census plot(cdate,pop,'o') %% % Create a fit options object and a fit type for the custom nonlinear model % $y = a(x-b)^n$, where _a_ and _b_ are coefficients and _n_ is a problem-dependent % parameter. fo = fitoptions('Method','NonlinearLeastSquares',... 'Lower',[0,0],... 'Upper',[Inf,max(cdate)],... 'StartPoint',[1 1]); ft = fittype('a*(x-b)^n','problem','n','options',fo); %% % Fit the data using the fit options and a value of _n_ = 2. [curve2,gof2] = fit(cdate,pop,ft,'problem',2) %% % Fit the data using the fit options and a value of _n_ = 3. [curve3,gof3] = fit(cdate,pop,ft,'problem',3) %% % Plot the fit results with the data. hold on plot(curve2,'m') plot(curve3,'c') legend('Data','n=2','n=3') hold off