by ncforest

在6.X中可以用findobj获取句柄，用get获取数据
% program by ncforest
% get data from ezplot figure
clear all;
subplot (1,2,1);
ezplot('y^2+x');
Handle=findobj(gca,'Type','Line');
xData= get(Handle,'xData');
yData= get(Handle,'yData');

在7.X中可以直接将图形句柄赋给一个变量
Handle=ezplot('y^2+x');
xData= get(Handle,'xData');
yData= get(Handle,'yData');

从获得的数据中推测其表达式，并显示其图形
% %get the expression from the data and show it's figure
% %by ncforest
% for n=1:5
%     [a,S]=polyfit(xData,yData,2);
%     A{n}=a;
%     da=dy*sqrt(diag(inv(S.R'*S.R)));
%     DA{n}=da';
%     freedom(n)=S.df;
%     [ye,delta]=polyval(a,x,S);
%     YE{n}=ye;
%     D{n}=delta;
%     chi2(n)=sum((y-ye).^2)/dy/dy;
% end
% Q=1-chi2cdf(chi2,freedom);