二分法在很多地方應該都會見到，這裡是透過二分法迭代逼近的方法求出一個方程的根。

function xc = bisection(f,a,b,tol)

% use the bisection method to find the root of the function

% Page 30,computer problem 7(Bisection method)

% input:

% f:the function that transform from the equation

% a,b:the left and right value of the interval which the root is in% tol:the accuracy

% output:

% xc:the solution of the equationif sign(f(a)) * sign(f(b)) >=0

error("f(a)f(b)

disp("The function should at least include 3 parameters");endif nargin == 3

tol = 10^-6;endwhile (b-a)/2 > tol

c = (a + b)/2;

if f(c) == 0 % when f(c) == 0,c is a root of the function

break

end

if f(a) * f(c)

% a and c form a new interval

b = c; else % c and b form a new interval

a = c; endendxc = (a+b)/2; % the mid_rang is the root that we find