matlab 中类的文件格式以及使用

This error message is related to the use of symbolic variables and expressions in MATLAB.

It occurs when there is a mistake in the syntax used to define or index a symbolic variable or expression.

For example, if you try to index a symbolic variable using a syntax that is not valid in MATLAB (e.g., using parentheses instead of curly braces), you will get this error.

Similarly, if you try to define a function using invalid syntax (such as using non-symbolic variables as function arguments or using non-sym expressions in the function body), you will also get this error.

To resolve this error, you need to carefully check the syntax of your code and ensure that you are using valid MATLAB indexing and symbolic expressions.