解高次幂微分方程

713753

我做了两个function去解这个方程。大侠们，看这么做对吗？

1. function [x, y, yInt] =odeSolver()
   
2. rhs = odeSolver(x,z)
   
3. %
   
4. % Input
   
5. % z: solution variable
   
6. % x: derivative variable
   
7. %
   
8. % Output:
   
9. % rhs: right hand side of the ODE
   
10. % dz/dx = F(z,x)
    
11. rhs = cos(x);
    
12. The second one.
    
13. function dzdx =ODErhs(x,z)
    
14. %
    
15. % Input:
    
16. % z: vector variable
    
17. % x: position
    
18. %
    
19. % Output:
    
20. % dzdx: RHS of the ODE system
    
21. dzdx = [z(2);z(3); x*z(1)*z(2)+0.8];
    
22. The third one.
    
23. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    
24. % question7 ODE
    
25. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    
26. % Clear memory and screen
    
27. clear all; clc
    
28. % Data ----------------------------------------
    
29. % Interval
    
30. a = 0.8;
    
31. b = 4.3;
    
32. % Initial condition
    
33. Z0 = [0.1376 0.204 -6952];
    
34. % Computations --------------------------------
    
35. % Solve the ODE
    
36. sol = ode45(@ODErhs, [a,b], Z0);
    
37. % Output --------------------------------------
    
38. plot(sol.x, sol.y(1,:))
    
39. xlabel('x')
    
40. ylabel('y')
    
41. title('question 7ode')

复制代码

还有就是X,Y两个量的近似解我搞出来了，可是我不懂怎么去求这个 yint。

yint是一个以实数形式表示的“y的近似解的积分”

原版英文题目解释是这样的。

A real number representing the integral of the approximate solution in the interval

where the differential equation has been solved.

有大侠会吗？

求救。

感恩。

happy

买看懂的程序，这是你自己编写的 还是从什么地方来的？
高阶微分方程求解方法一般和二阶的都是一样的，用ode45实现就可以了