非线性最小二乘法matlab代码
时间: 2023-10-14 19:06:32 浏览: 27
以下是一个基本的非线性最小二乘法的 Matlab 代码:
```matlab
function [x,resnorm,residual,exitflag,output] = mylsqnonlin(fun,x0,LB,UB,options,varargin)
% Nonlinear least squares solver
% fun - function handle to the nonlinear function
% x0 - initial guess
% LB, UB - lower and upper bounds for the variables
% options - options structure
% varargin - additional arguments to be passed to fun
% x - solution
% resnorm - squared 2-norm of the residual at the solution
% residual - the residual vector at the solution
% exitflag - exit flag
% output - structure containing information about the optimization
% process
% Set default options
if nargin < 5 || isempty(options)
options = optimset('lsqnonlin');
end
% Set default lower and upper bounds
if nargin < 3 || isempty(LB)
LB = -inf(size(x0));
end
if nargin < 4 || isempty(UB)
UB = inf(size(x0));
end
% Solve the problem
[x,resnorm,residual,exitflag,output] = lsqnonlin(@(x)myfun(x,fun,varargin{:}),x0,LB,UB,options);
end
function [f,J] = myfun(x,fun,varargin)
% Compute the function and the Jacobian
if nargout == 1
f = fun(x,varargin{:});
else
[f,J] = fun(x,varargin{:});
end
end
```
其中,`fun`是用来计算残差向量的函数句柄,`x0`是初始猜测,`LB`和`UB`是变量的上下限,`options`是一个选项结构体,`varargin`是传递给`fun`的额外参数。函数`mylsqnonlin`在调用`lsqnonlin`进行求解之前,对输入参数进行了一些处理,同时也提供了一些默认值。函数`myfun`用来计算残差向量和Jacobian矩阵。