function x=newtondiedai(x0,n,e) %方程求根牛頓迭代(課本137頁例5)

for k=1:n
    k
    
    
    if x0==-1
        '奇異'
        break
    else
        x1=x0-(x0-exp(-x0))/(1+x0);
    end
    if abs(x1-x0)<e
        x=x1;
        break
    else
        if k==n
            '迭代失敗'
        else
            x0=x1;
        end
    end
    x1
    
end

x=x1;