The ‘limit’ function in MATLAB which is a part of the Symbolic Math Toolbox, is designed to operate on symbolic variables and symbolic expressions. When the function ‘cftool’ from the Curve Fitting Toolbox creates a fitted model, it returns a ‘cfit’ object. A ‘cfit’ object is an object that encapsulates the fitted function, but it is not a symbolic expression, hence does not work with ‘cftool’ function.
To enable symbolic analysis, the object created by the ‘cfit’ function must first be converted into a symbolic expression using the ‘formula’ function:
fexpr = formula(fittedmodel);
Once in symbolic form, MATLAB’s Symbolic Math Toolbox can be used to compute the limit of the function as the independent variable approaches a specified value.
For detailed information on these functions, please refer to the following documentation:
- https://www.mathworks.com/help/curvefit/cfit.formula.html
- https://www.mathworks.com/help/curvefit/curve-and-surface-fitting-objects-and-object-functions.html
I hope this helps!
