Help me, Error using inline (line 51) Input must be a character vector.

q=get(handles.fo,'string');
syms x;
f=inline(q);
w=diff(f(x));
f2=inline(w);
xo=str2num(get(handles.xo,'string'));
x=xo

for i=0:1000
    y=x
    x=y-(f(x)/f2(x));
    if x==y
        break
    end
end
x=num2str(x);
i=num2str(i);
set(handles.rootout,'string',x)
set(handles.iterout,'string',i)

[Jan]

Without any description of what you want to do, an answer needs bold guessing. The error message is actually clear: inline works with char vectors only, but you provide a symbolic expression.

Note: The case x==y is very unlikely due to rounding effects. Better use a certain limit.

[Steven Lord]

Extending Jan's answer, stop using inline. As its documentation page states, you should be using anonymous functions instead. The matlabFunction function can convert a symbolic expression into a function file or an anonymous function.

[Muhammad Lazuardi Afnan Ghifari]

Thank you for your answer sir, actually im not fully understand with that. Is that mean i can't use funtion inline anymore? I have task to make a GUI using matlab and the funtion is x.^2+10*cos(x), it work perfectly when im not use the GUI math script but it keep error when i want to make GUI

[Walter Roberson]

Unless you are using MATLAB 4.2 or earlier, you should not use inline()