为什么我得到fminsearch未定义函数错误

问题描述

我正在尝试使用2个输入优化函数.尝试使用fminsearch，但是尽管已经定义了fminsearch，但它总是说未定义的函数或变量.

I'm trying to optimize a function with 2 inputs. Trying to use fminsearch but it keeps saying undefined function or variable although it is already defined.

我已经在与主脚本位于同一目录中的单独脚本中定义了该函数.我有一个包含优化工具箱的教室许可证，调用该函数时没有拼写错误.

I have already defined the function in a separate script that is in the same directory with my main script. I have a classroom license which includes optimization toolbox and there is no spelling mistake while calling the function.

function o=u(x,y)
%some code here
end

%in a second script

init=[0.1,0.1];

b=fminsearch(o,init);

错误是:

推荐答案

摘录自 fminsearch ，要最小化的函数必须具有单个参数，并使用功能句柄(请参阅与此相关的 answer ).

From the documentation on fminsearch, the function being minimized must have a single argument and accessed with a function handle (see this related answer).

您遇到的错误是因为您无法调用o并将其用作fminsearch()的输入，因为o是未定义的.要获取o，您必须首先获取u(x,y)，此外，如前所述，fminsearch需要函数句柄作为输入.

The error you are getting is because you can't call o and use it as an input to fminsearch() since o is undefined. To get o, you have to first get u(x,y), plus as mentioned, fminsearch requires a function handle as an input.

您有几个选项仍使用独立功能，u(x,y).

1.创建功能句柄
定义一个调用u(x,y)但具有单个参数的函数句柄，该参数是2 x 1向量z = [x; y].

1. Create a function handle
Define a function handle that calls u(x,y) but has a single argument which is a 2 x 1 vector, z = [x; y].

fh =@(z) u(z(1),z(2));
z0 = [1; 2];                         % Initial Guess for z = [x; y]
[z,TC] = fminsearch(fh,z0)

2.更改功能并直接调用

使用

[z,TC] = fminsearch(@u,z0)

如果将u(x,y)重新定义为以下内容:

if you redefine u(x,y) to be as follows:

function o=u(z)
   x = z(1);
   y = z(2);
   % your function code here
end

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