%Get the input for the function and the convergence criteria
sfnc = input('Enter the function : ', 's');
fnc = inline(sfnc, 'x');
criteria = input('Enter the convergence criteria : ');
fa = 1;
fb = 1;

%Decide on an interval using input and checking whether a root definitely
%exists within it
while ((fa*fb) > 0) %loops while the statement is false, when true it stops
                    %and the message below is displayed in the if statement.
    a = input('Enter the lower limit of the interval : ');
    b = input('Enter the upper limit of the interval : ');
    fa = fnc(a);
    fb = fnc(b);
    x1=a;
    x2=b;

    xtrue = fzero(fnc, [b a]); %determines the true root of the function between [a,b]

    clc
    if ((fa*fb) > 0)
        display('Please enter an interval such that f(a)*f(b) is negative.');
    end;
end