What's wrong with the folow function?

f is my input function and I have to verify if it converges. It appears: "Error using inline/feval (line 23)Not enough inputs to inline function."

df = diff(f); 

f2 = diff(df); 

f1 = inline(char(f));

df1 = inline(char(df));

df2 = inline(char(f2));

c=1;

       if (feval(f1,a)*feval(f1,b)>=0)   

     disp('No')

  c=0;

  return

else  

      if (feval(df1,a)*feval(df1,b)<=0) 

    disp(' No')

    c=0;

  return
    end

end

What could it be?

Answer 1

[Walter Roberson]

You have not shown us how you constructed f. You have not used it in the manner I showed in http://www.mathworks.co.uk/matlabcentral/answers/108360-what-s-wrong-with-the-folow-expression

Please show f, and please show class(f) and symvar(f)