【已解决】自编的牛顿拉夫森程序中norm函数的问题

luckyrhkr

我把MyP_test里的内容在matlab里面一步一步直接输入时没有问题。但是调用MyP_test函数时问题出错。提示牛顿拉夫森程序中norm函数部分有问题：
??? Undefined function or method 'norm' for input arguments of type 'sym'.
Error in ==> MyP_test at 75
    err = norm(Q-x');
Error in ==> Run at 8
[FF]=MyP_test(e,x,0.5,2,2);
那位能帮我看看是怎么回事嘛？

程序如下：

1. 
   
2. clc;clear all;
   
3. %input rule
   
4. %q1=x1  q2=y1 q3=phi1;
   
5. %q4=x2  q5=y2 q6=phi2;
   
6. syms q1 q2 q3 q4 q5 q6 t
   
7. x=[0.5,-0.866,5.236,1.5,-1,6.14]
   
8. e=[q1-cos(q3);q2-sin(q3);q4-cos(q3)-cos(q6);q5-sin(q3)-sin(q6);q5+1;q3-pi/6*t-5*pi/3]
   
9. [FF]=MyP_test(e,x,0.5,2,2);
   

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MyP_test程序：

1. 
   
2. function [P,V,A]=MyP_test(e,x,deltaT,totalT,BadyNum, tol, epsilon, max1)
   
3. syms t
   
4. %Initialize The Variables
   
5. % Input  e:  Nonlinear Algebraic Equations；
   
6. %   x:   Initial Value;
   
7. %   tol:  Solution Error Tolerance; epsilon:  Equation Error Tolerance;
   
8. %   max1: Maximum Number of Iteration allowed;
   
9. %           deltaT
   
10. %           totalT
    
11. %           BadyNum
    
12. %Out  P:  Solution of Equations;
    
13. %   iter:  Number of Iterations;  err:  Error
    
14. %   Tolerance;
    
15. if nargin<2
    
16. &#160; &#160; error('At least two input parameters')
    
17. end
    
18. if nargin<3||isempty(deltaT)
    
19. &#160; &#160; deltaT=1;
    
20. end
    
21. if nargin<4||isempty(totalT)
    
22. &#160; &#160; totalT=2;
    
23. end
    
24. if nargin<5||isempty(BadyNum)
    
25. &#160; &#160; BadyNum=2;
    
26. end
    
27. if nargin<6||isempty(tol)
    
28. &#160; &#160; tol=10e-4;
    
29. end
    
30. if nargin<7||isempty(epsilon)
    
31. &#160; &#160; epsilon=10e-4;
    
32. end
    
33. if nargin<8||isempty(max1)
    
34. &#160; &#160; max1=25;
    
35. end
    
36. 
    
37. for ii=1:numel(e)
    
38. &#160; &#160; qq(ii)=strcat({'q'},num2str(ii))&#160; &#160; ;%qq is is to calculate Jacobian Matrix
    
39. end
    
40. for ii=1:numel(e)
    
41. qqq(ii)=sym(['q',num2str(ii)]);&#160; &#160;&#160; &#160;%qqq is for the formation of Jacobian Matrix&#160;&#160;
    
42. end
    
43. %Jacobian Matrix
    
44. Jq=jacobian(e,qqq);&#160; &#160;
    
45. %%Velocity Equ
    
46. Jt=jacobian(e,t);
    
47. nu=-Jt;&#160; &#160;&#160; &#160;&#160; &#160;&#160; &#160;&#160; &#160;&#160;&#160;
    
48. [dq]=Jq\nu;
    
49. %%Acceleration Equ
    
50. for kk=1:length(x)
    
51. &#160; &#160; Jqt=diff(Jq,qqq(kk));
    
52. &#160; &#160; Jqq(:,kk)=Jqt(:,kk);
    
53. end
    
54. gamma=-Jqq*dq.^2-2*diff(Jq,t)*dq-diff(Jt,t);&#160; &#160;
    
55. [ddq]=Jq\gamma;
    
56. %Assembly
    
57. jj=1;
    
58. for t = 0 : deltaT : totalT
    
59. &#160; &#160; for ii=1:length(x)
    
60. &#160; &#160; syms(['q',num2str(ii)]);
    
61. &#160; &#160; end
    
62. % NEWTON-RAPHSON METHOD FOR NONLINEAR EQUATIONS
    
63. ee=subs(e);
    
64. arrayfun(@(q)(assignin('base', qq{q}, x(q))),1:length(x));
    
65. A=subs(Jq);
    
66. b = -subs(ee);
    
67. for k = 1 : max1
    
68. &#160; &#160; xx=A\b;
    
69. &#160; &#160; Q = x.' - xx;
    
70. &#160; &#160; arrayfun(@(q)(assignin('base', qq{q}, Q(q))),1:length(Q));
    
71. &#160; &#160; Z = -subs(ee);
    
72. &#160; &#160; err = norm(Q-x');
    
73. &#160; &#160; relerr = err/(norm(Q)+eps);
    
74. &#160; &#160; x = Q;
    
75. &#160; &#160; b = Z;
    
76. &#160; &#160; iter = k;
    
77. &#160; &#160; if (err<tol)&#160;&#160;|| (relerr<tol)&#160;&#160;|| (abs(b)<epsilon)
    
78. &#160; &#160;&#160; &#160;&#160;&#160;break;
    
79. &#160; &#160; end
    
80. end
    
81. arrayfun(@(q)(assignin('base', qq{q}, x(q))),1:length(x));
    
82. P(:,jj)=x;
    
83. V(:,jj)=subs(dq);
    
84. A(:,jj)=subs(ddq);
    
85. jj=jj+1;
    
86. end
    

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qibbxxt

1. norm

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不支持符号变量的重载方法

luckyrhkr

恩，我只好把Q-x'拿出来单独定义了一下。