newton.m

来自「非线性方程组解法源代码」· M 代码 · 共 31 行

function Newton
%牛顿法解方程
syms x y diff_y;
y = input('请输入迭代函数f(x)：');
v = input('请输入迭代条件[x0,e1,e2,N]:');
x0 = v(1);
e1 = v(2);
e2 = v(3);
N = v(4);
diff_y = diff(y);
falg = 0;
for k = 1:N
    x = x0;
    if abs(eval(y))<e1
        x0
        flag = 1;
        break;
    else
        x1 = x0 - eval(y)/eval(diff_y);
        if abs(x1-x0)<e2
            x1
            flag = 1;
            break;
        else
            x0 = x1;
        end
    end
end
if flag == 0
    disp('迭代失败！');
end