最速下降梯度法matlab程序

AaronSpark

1. % Steepest Descent Method
   
2. % By Kshitij Deshpande
   
3. clc
   
4. clear all
   
5. warning off
   
6. prompt = {'Coeficients if X1=','Coefficients of X2=','Coefficeint of X1X2=','Initial Point='};
   
7. def = {'[2 1 0]','[1 -1 0]','2','[0 0]'};
   
8. a=inputdlg(prompt,'Data',1,def);
   
9. a=char(a);
   
10. [m,n]=size(a);
    
11. x1 = eval(a(1,1:n));x2=eval(a(2,1:n));x1x2=eval(a(3,1:n));X1=eval(a(4,1:n));
    
12. delf1(1) = polyval(polyder(x1),X1(1));
    
13. delf1(1) = (delf1(1))+(x1x2*X1(2));
    
14. delf1(2) = polyval(polyder(x2),X1(1));
    
15. delf1(2) = (delf1(2))+(x1x2*X1(1));
    
16. s=-delf1;
    
17. %%%%%%%%%%
    
18. %report
    
19. srep(1,1:2)=s;
    
20. %%%%%%%%%%
    
21. x1new(1)=s(1)^2;x1new(2)=2*X1(1)*s(1);x1new(3) = X1(1)^2;
    
22. x1new=x1new*x1(1);
    
23. x1new_(2)=x1(2)*s(1);x1new_(3)=x1(2)*X1(1);
    
24. x1new = x1new+x1new_;
    
25. 
    
26. x2new(1)=s(2)^2;x2new(2)=2*X1(2)*s(2);x2new(3) = X1(2)^2;
    
27. x2new=x2new*x2(1);
    
28. x2new_(2)=x2(2)*s(2);x2new_(3)=x2(2)*X1(2);
    
29. x2new = x2new+x2new_;
    
30. x1x2new(1)=s(1)*s(2);x1x2new(2)=X1(1)*s(2)+X1(2)*s(1);x1x2new(3)=X1(1)*X1(2);
    
31. x1x2new=x1x2*x1x2new;
    
32. df = polyder(x1new+x2new+x1x2new);
    
33. lambda(1) = roots(df);
    
34. 
    
35. X1=X1+lambda(1)*s;
    
36. Xrep(1,1:2)=X1;
    
37. delf1(1) = polyval(polyder(x1),X1(1));
    
38. delf1(1) = (delf1(1))+(x1x2*X1(2));
    
39. delf1(2) = polyval(polyder(x2),X1(2));
    
40. delf1(2) = (delf1(2))+(x1x2*X1(1));
    
41. if all(X1)== 0
    
42. fprintf('%d %d is the optimum point',X1(1),X1(2));
    
43. end
    
44. itrep(1)=1;
    
45. it=2;
    
46. while all(delf1)==1
    
47. s=-delf1;
    
48. x1new(1)=s(1)^2;x1new(2)=2*X1(1)*s(1);x1new(3) = X1(1)^2;
    
49. x1new=x1new*x1(1);
    
50. x1new_(2)=x1(2)*s(1);x1new_(3)=x1(2)*X1(1);
    
51. x1new = x1new+x1new_;
    
52. 
    
53. x2new(1)=s(2)^2;x2new(2)=2*X1(2)*s(2);x2new(3) = X1(2)^2;
    
54. x2new=x2new*x2(1);
    
55. x2new_(2)=x2(2)*s(2);x2new_(3)=x2(2)*X1(2);
    
56. x2new = x2new+x2new_;
    
57. x1x2new(1)=s(1)*s(2);x1x2new(2)=X1(1)*s(2)+X1(2)*s(1);x1x2new(3)=X1(1)*X1(2);
    
58. x1x2new=x1x2*x1x2new;
    
59. df = polyder(x1new+x2new+x1x2new);
    
60. lambda(it) = roots(df);
    
61. X1=X1+lambda(it)*s;
    
62. delf1(1) = polyval(polyder(x1),X1(1));
    
63. delf1(1) = (delf1(1))+(x1x2*X1(2));
    
64. delf1(2) = polyval(polyder(x2),X1(2));
    
65. delf1(2) = (delf1(2))+(x1x2*X1(1));
    
66. itrep(it)=it;
    
67. srep(it,1:2)=s;
    
68. Xrep(it,1:2)=X1;
    
69. it=it+1;
    
70. end
    
71. [m,n]=size(itrep);
    
72. matrix=[itrep' srep(1:n,1) srep(1:n,2) Xrep(1:n,1) Xrep(1:n,2)];
    
73. answer = char(num2str(X1));
    
74. answer = ['The optimal point is [' answer ']'];
    
75. msgbox(answer,'Solution');
    
76. disp(' Press Any key to View Detailed Report............');
    
77. pause
    
78. echo off
    
79. report steep;
    
80. clc

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[ 本帖最后由 suffer 于 2006-10-9 20:37 编辑 ]

broad

这个是用什么语言写的?有点没看懂  土人啊~~

pheigenbau

<P>最速下降法我一直都没学会,看来我的水平还很差</P>

hanzhenhui

看到程序才感到自己真应该在细读基础课本了。

leehuge2008

把这些常用的数学算法编程实现太让我们感谢了！盼多见到这类作品亚

suffer

原帖由 broad 于 2006-5-15 22:02 发表
这个是用什么语言写的?有点没看懂  土人啊~~

当然是matlab版了，没看这里是matlab实例赏析吗？

freeway

有没有共轭梯度的算法实现啊

suffer

原帖由 freeway 于 2006-10-10 22:50 发表
有没有共轭梯度的算法实现啊

http://forum.vibunion.com/forum/viewthread.php?tid=27826

[ 本帖最后由 eight 于 2007-2-3 17:48 编辑 ]

suffer

原帖由 freeway 于 2006-10-10 22:50 发表
有没有共轭梯度的算法实现啊

http://forum.vibunion.com/forum/viewthread.php?tid=28933

[ 本帖最后由 eight 于 2007-2-3 17:48 编辑 ]