[交流] 【求助】求助，拟合参数，急。。。。已有3人参与

Originally posted by liuyalei820 at 2010-06-17 14:24:08:
x=[0.8,1.0,1.2,1.6,2.0];
y=[3.03,1.55,0.9,0.38,0.19];
y=A*(1-w/(R*x))*exp(-R*x)+B*(1-w/(g*x))*exp(-g*x)+w*2.714/x;
参数为A,B,R,w,g
求参数值。

Originally posted by lijinfeng042 at 2010-06-17 14:57:41:

直接也可以

General model:
     f(x) = A*(1-w/(R*x))*exp(-R*x)+B*(1-w/(g*x))*exp(-g*x)+w*2.714/x
Coefficients:
       A =   -0.002875
       B =      -2.971
       R =   -0.001061
        ...

function tu
x=[0.8,1.0,1.2,1.6,2.0]
y=[3.03,1.55,0.9,0.38,0.19]
plot(x,y,'o')
axis([0 2 0 1])
f=inline('b(:,1).*(1-b(:,2)./(b(:,3)*x)).*exp(-b(:,3).*x)+b(:,4).*(1-b(:,2)./(b(:,5).*x)).*exp(-b(:,5).*x)+b(:,2).*2.714./x','b','x')
b=ones(1,5)
[beta,resnorm,residual,exitflag]=lsqcurvefit(f,b,x,y)
syms b x
b=beta
y=subs(b(:,1).*(1-b(:,2)./(b(:,3)*x)).*exp(-b(:,3).*x)+b(:,4).*(1-b(:,2)./(b(:,5).*x)).*exp(-b(:,5).*x)+b(:,2).*2.714./x)
hold on
ezplot(y,[0 2])