function erfen
%二分法解方程
syms x y ;
y = input('請輸入迭代函數f(x)：');
v = input('請輸入迭代條件[a,b,e]:');
a = v(1);
b = v(2);
e = v(3);
while abs(b-a)>e
    c = 0.5 * (a + b);
    x = c;
    fc = eval(y);
    x = a;
    fa = eval(y);
    if fc==0
        c
    elseif fa==0
        a
    elseif fa*fc>0
        a = c;
    else
        b = c;
    end
end
a
b
0.5 * (a + b)