matlab拟合指定反比例函数，急，在线等，谢谢

使用nlinfit进行非线性拟合。程序如下：

x= [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

y = [0, -44, -427, -501, -549, -580, -596, -686, -709, -727];

f = @(beta, x)beta(1)./(x+beta(2))+beta(3);

beta = nlinfit(x, y, f, [0; 0; 0]);

a = beta(1), b = beta(2), c = beta(3)

xx = 1:.1:10;

yy = a./(xx+b)+c;

plot(x, y, 'o', xx, yy)

输出：

%%%%%%%%%%%%%%%            程序              %%%%%%%%%%%%%%%%%%%%%%

clear

clc

syms t

x=[239:1:341]';

y=[-2799,-2799,-2799,-2799,-2799,-2799,-2823,-2823,-2823,-2823,...

    -2823,-2823,-2823,-2823,-2852,-2852,-2852,-2852,-2852,-2864,-2864,...

    -2864,-2864,-2864,-2864,-2873,-2873,-2873,-2873,-2873,-2873,-2873,...

    -2893,-2893,-2893,-2893,-2893,-2893,-2899,-2899,-2899,-2899,-2899,...

    -2899,-2899,-2907,-2907,-2907,-2907,-2907,-2907,-2907,-2923,-2923,...

    -2923,-2923,-2923,-2923,-2927,-2927,-2927,-2927,-2927,-2927,-2927,...

    -2927,-2942,-2942,-2942,-2942,-2942,-2942,-2942,-2942,-2942,-2953,...

    -2953,-2953,-2953,-2956,-2956,-2956,-2956,-2956,-2956,-2956,-2973,...

    -2973,-2973,-2973,-2973,-2973,-2973,-2973,-2973,-2973,-2973,-2973,...

    -2973,-2973,-2973,-2973,-2973]';

% plot(x,y);

f = fittype('a/(t+b)+c','independent','t','coefficients',{'a','b','c'});

opt = fitoptions(f);

set(opt,'startpoint',[1 1 1]);

cfun = fit(x,y,f,opt)

yy = cfun(x);

plot(x,y,'*',x,yy,'r');

legend('原始数据点','拟合后曲线');

%%%%%%%%%%%%%     结果                   %%%%%%%%%%%%%%%%%%%

cfun = 

     General model:

     cfun(t) = a/(t+b)+c

     Coefficients (with 95% confidence bounds):

       a =   2.096e+04  (1.662e+04, 2.529e+04)

       b =        -171  (-181.5, -160.6)

       c =       -3095  (-3116, -3075)

a，b，c为拟合的系数，95%为置信区间

%%%%%%%%%%%%%%     图像对比          %%%%%%%%%%%%%%%%%%%