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发表于 2012-2-16 16:33:38
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来自 江苏扬州
clear, clc
x=[...]';
y=[...]';
fx=@(b,t)(b(1)+b(2)*t+b(3)*t.^2)./(1+b(4)*t+b(5)*exp(b(6)*t));
b=[0.4 2 0.0012 3.546 -0.215 -0.49];
% folowing is the fitting process
for l=1:5
b=lsqcurvefit(fx,b,x,y)
b=nlinfit(x,y,fx,b)
end
y1=fx(b,x);
RSS=(y-y1)'*(y-y1),%residual sum of squares
n=length(y);
SSy=var(y)*(n-1), %total SS of y variable
R2=(SSy-RSS)/SSy, %R square
figure(1),clf
x1=linspace(min(x),max(x),250);
y1=fx(b,x1);
plot(x,y,'ko','markerfacecolor','k')
hold on
plot(x1,y1,'r-','linewidth',2)
legend('data','fit','location','best')
axis tight |
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