解方程的二分法 matlab 程序

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解方程的二分法  matlab 程序  （ x^3-3*x^2+6*x-1=0）

2 R6 u5 |! E' k; h$ M; l% Bisection.m
function[k,x,f_value]=Bisection(f,a,b,eps1,eps2,N)
fprintf('k ,a ,b ,x, f\n')
- V; H/ a. c0 j+ d7 f3 Z/ ^for k=1:N
    x=(a+b)/2;
- ?7 U8 \$ Y2 g7 f- ]  u" i    f_value=f(x);
    fprintf( '%3d, %10.9f, %10.9f, %10.9f,%10.9f,\n'...
0 p, z8 l; Y( b/ u. ^7 q3 T, q$ e      ,k ,a ,b ,x, f_value)
    if abs(f_value)< eps1||0.5*(b-a)<eps2
5 l2 |5 S* W& s+ u    return
    else
        if f(x)*f(a)<0
4 D# L' @5 c( H& B9 @: ^& b          b=x;
& V' p& O5 ~3 d9 @        else
          a=x;
        end
% X; w0 h0 D5 |% P3 o) m        if k== N
          warning ('算法超出最大迭代數!')   
        end
    end

  A! b& f2 J% Q% examlpe7.m
a=0; b=1;
. O) U$ Z) d( F3 ~: t% Y! Jeps1=1e-4;eps2=1e-4;
N=300;
8 ~$ r/ ?5 ?" Pf=@ (x) (x^3-3*x^2+6*x-1);
$ U9 u# f4 t7 z6 t) U7 e# uHfun=@Bisection;
1 c" q, D+ }% ]7 _3 `2 F[k,x,f_value]= feval(Hfun, f,a,b,eps1,eps2,N);

運行結果
>> examlpe7
k ,a ,b ,x, f
) A+ P$ j+ l8 V2 L) o3 S  1, 0.000000000, 1.000000000, 0.500000000,1.375000000,
  2, 0.000000000, 0.500000000, 0.250000000,0.328125000,
3 ]' i4 k/ x7 r$ h1 g6 o+ L  3, 0.000000000, 0.250000000, 0.125000000,-0.294921875,
# R7 @( U  C6 t$ r4 m  4, 0.125000000, 0.250000000, 0.187500000,0.026123047,
/ t0 F$ r0 |9 ~8 J; ?) m2 _+ t  5, 0.125000000, 0.187500000, 0.156250000,-0.131927490,
  6, 0.156250000, 0.187500000, 0.171875000,-0.052295685,
  7, 0.171875000, 0.187500000, 0.179687500,-0.012936115,
3 O6 |& C% u9 e; Y$ e9 a/ m  8, 0.179687500, 0.187500000, 0.183593750,0.006630838,
$ b9 }6 M9 B0 A% [' G+ q1 l" b' f, q  9, 0.179687500, 0.183593750, 0.181640625,-0.003143273,
10, 0.181640625, 0.183593750, 0.182617188,0.001746121,
9 s  y8 S) t7 B- A( R% h 11, 0.181640625, 0.182617188, 0.182128906,-0.000697991,
+ b1 p7 R/ X1 V& [ 12, 0.182128906, 0.182617188, 0.182373047,0.000524211,
7 R+ w. d! O3 P2 p/ A 13, 0.182128906, 0.182373047, 0.182250977,-0.000086854,
* R+ Q$ H$ n1 a' U' L

( q  Y$ z4 {& _