clear;clc;
load 1.mat;--------------------------------------------------------------（1.mat是我调用的数据）
X = [x, y];
beta0 = [1, 1, 2, 1, 0, 1];
[beta, r, J, COVB, mse] = nlinfit(X, z, @myfun, beta0);

% 画图
plot3(x, y, z, '*');
hold on;
xx = 1:1:50;
yy = 1:40;
[xx1, yy1] = meshgrid(xx', yy);
xx2 = xx1(:);
yy2 = yy1(:);
zz2 = myfun(beta, [xx2, yy2]);
zz1 = reshape(zz2, length(yy), length(xx));
mesh(xx1, yy1, zz1);

F = myfun2(xx2, yy2);
zz3 = reshape(F, length(yy), length(xx));
C = ones(length(yy), length(xx));
C = C / 2;
mesh(xx1, yy1, zz3, C);

modelfun = @(b,x)(b(1)+b(2)*exp(-b(3)*x));

rng('default') % for reproducibility
b = [1;3;2];
x = exprnd(2,100,1);
y = modelfun(b,x) + normrnd(0,0.1,100,1);
Set robust fitting options.

opts = statset('nlinfit');
opts.RobustWgtFun = 'bisquare';
Fit the nonlinear model using the robust fitting options.

beta0 = [2;2;2];
beta = nlinfit(x,y,modelfun,beta0,opts)