代码如下:
function rtn=newton1(fx,dfx,x0,tol,N)
% Newton Method
% The first parameter fx is a external function with respect to viable x.
% The second parameter dfx is the first order diffential function of fx.
% x0 is initial iteration point.
% tol is the tolerance of the loop.
% N is the maximum number of iterations.
x=x0;f0=eval_r(fx);df0=eval_r(dfx);
n=0;
disp('   [   n        xn          xn+1           fn+1  ]');
while n<=N
    x1=x0-f0/df0;
    x=x1;f1=eval_r(fx);
    X=[n,x0,x1,f1];
    disp(X);
    if abs(x0-x1)        fprintf('The procedure was successful.')
        return
    else 
        n=n+1;
        x0=x1;f0=f1;
    end
end
if n==N+1
    fprintf('the method failed after N iterations. '),
end

保存为:newton1.m

运行如下:
>>fx='x-exp(-x)';
>>dfx='1+exp(-x)';
>>newton1(fx,dfx,.5,10^(-5),10)
[   n        xn          xn+1           fn+1  ]
         0    0.5000    0.5663   -0.0013

    1.0000    0.5663    0.5671   -0.0000

    2.0000    0.5671    0.5671   -0.0000

    3.0000    0.5671    0.5671   -0.0000

The procedure was successful.

最后求出的根为:0.5671