www.gusucode.com > curvefit 案例源码程序 matlab代码 > curvefit/CustomNonlinearCensusFittingExample.m
%% Custom Nonlinear Census Fitting % This example shows how to fit a custom equation to census data, % specifying bounds, coefficients, and a problem-dependent parameter. %% % Load and plot the data in census.mat: % Copyright 2015 The MathWorks, Inc. load census plot(cdate,pop,'o') hold on %% % Create a fit options structure and a fittype object for the custom % nonlinear model y = a(x-b)n, where a and b are coefficients and n is a % problem-dependent parameter. See the fittype function page for more details on % problem-dependent parameters. s = fitoptions('Method','NonlinearLeastSquares',... 'Lower',[0,0],... 'Upper',[Inf,max(cdate)],... 'Startpoint',[1 1]); f = fittype('a*(x-b)^n','problem','n','options',s); %% % Fit the data using the fit options and a value of n = 2: [c2,gof2] = fit(cdate,pop,f,'problem',2) %% % Fit the data using the fit options and a value of n = 3: [c3,gof3] = fit(cdate,pop,f,'problem',3) %% % Plot the fit results and the data: plot(c2,'m') plot(c3,'c') legend( 'fit with n=2', 'fit with n=3' )