Newton-Raphson MATLAB

function newton(f,df,x0,tol,Nmax)

    syms x;%Setting x to be a symbolic variable

    %Defining the variables

    %f=input('Enter your function here: ');
    %df=input('Enter your differentiated function here: ');
    %x0=input('Enter your initial estimation (if unknown, set as 0): ');
    %Nmax=input('Enter your max number of iterations here ');
    %tol=input('Enter your tolerance ');

    err=tol+1; %Sets error as larger than the tol to initiate the while loop
    n=0; %Creates the iteration counter

    if df==0;
        error('The differential of your function is 0, therefore iterations cannot begin.')
    end

    while err>tol;

        n=n+1;

        fv=subs(f,x,x0);
        fdv=subs(df,x,x0);
        x1=x0-((fv)/fdv);

        err=abs(x1-x0);
        x0=x1;

        if n>Nmax;
            error('The maximum number of iterations has been reached, therefore a solution has not been found.');
        end


        if err<tol;
            break
        end

    end
    fprintf('The root of your function is: %g \n', x0)
    fprintf('This took %d iterations to reach', n)

end