8楼: Originally posted by 津津爱睡觉 at 2015-07-20 14:09:49
想问下拟合的代码是什么啊。。我拟合出的结果都不对。。太感谢了，你让我觉得世界都亮了...

Variable  x,y ;
Function x=1/(x2*49.005^2)*(ln((y/x1)*((x1-49.005)/(y-49.005)))-49.005*(1/y-1./x1));
Data;
         0   83.9499
    0.2500   69.1806
    0.5000   63.7801
    0.7500   62.1649
    1.0000   60.6538
    1.2500   59.8982
    1.5000   58.4652
    1.7500   57.7097
    2.0000   56.9541
    2.5000   55.7696
    3.0000   54.9544
    3.5000   53.8983
    4.0000   53.1428
    4.5000   52.1404
    5.0000   51.6460
    5.5000   51.3437
    6.0000   51.1179
    6.5000   50.8551

LoopConstant x=[0,0.25,0.5,0.75,1,1.25,1.5,1.75,2,2.25,2.5,3,3.5,4,4.5,5,5.5,6,6.5];
Function
x=1/(15.3109*49.005^2)*(ln((y/86.4241)*((86.4241-49.005)/(y-49.005)))-49.005*(1/y-1/86.4241));

function solve_eqs
clear all;clc
format long

global x
y0=-0.1;
x_data=[0,0.25,0.5,0.75,1,1.25,1.5,1.75,2,2.25,2.5,3,3.5,4,4.5,5,5.5,6,6.5];
for i=1:length(x_data)
    x=x_data(i);
[y(i) fval(i)]=fsolve(@eqs,y0);
end

[x_data ;y; fval]'

2楼: Originally posted by dingd at 2015-07-20 10:55:11
用1stOpt很方便：

LoopConstant x=;
Function
x=1/(15.3109*49.005^2)*(ln((y/86.4241)*((86.4241-49.005)/(y-49.005)))-49.005*(1/y-1/86.4241));


x        y
0        -52.980531685766
0.25        -0.005325680664864
0 ...