24小时热门版块排行榜

返回列表

当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖

vista朱

木虫 (著名写手)

应助: 39 (小学生)
金币: 5493
散金: 348
红花: 42
帖子: 1891
在线: 331.9小时
虫号: 1930187
注册: 2012-08-08
性别: GG
专业: 动力学与控制

[求助] 紧急求助已有2人参与

用 ode45解下面非线性方程组，
clc
clear
syms  A1 A2 A3 B1 B2 B3 x2 x3 x4 x5 x6 x7 pho1 pho2 pho3 mdot_in h_in T_a1 T_a2 T_a3 T_r1 T_r2 T_r3 alpha_o1 alpha_o2 alpha_o3 alpha_i1 alpha_i2 alpha_i3;
a=[-2.8e-3,2.8e-3*pho1,0,0,0,0,0
2.8e-3*A1*(x2-x3)-2.8e-3, 2.8e-3*B1*(x2-x3), 2.8e-3*pho2,0,0,0,0
(2.8e-3*A2+2.8e-3*A1)*(x3-x4)-2.8e-3,2.8e-3*B1*(x3-x4),2.8e-3*B2*(x3-x4),2.8e-3*pho3,0,0,0
2.8e-3*(A1+A2+A3),2.8e-3*B1,2.8e-3*B2,2.8e-3*B3,0,0,0
0,0,0,0,2377,0,0
0,0,0,0,0,2377,0
0,0,0,0,0,0,2377];
c=[(mdot_in*(h_in-x2)+1.3*alpha_i1*(x5-T_r1));(mdot_in*(x2-x3)+1.3*alpha_i2*(x6-T_r2));(mdot_in*(x3-x4)+1.3*alpha_i3*(x7-T_r3));0;30.58*alpha_o1*(T_a3-x5)-1.3*alpha_i1*(x5-T_r1);30.58*alpha_o2*(T_a2-x6)-1.3*alpha_i2*(x6-T_r2);30.58*alpha_o3*(T_a1-x7)-1.3*alpha_i3*(x7-T_r3)];
bb=inv(a)*c;

用传统的ode方法编写
即
  dx(1)=  (2500*((13*alpha_i1*(T_r1 - x(5)))/10 - mdot_in*(h_in - x(2)))*(B1*pho2*pho3 - B1*B2*pho3*x(2) + B1*B2*pho3*x(3) - B1*B3*pho2*x(3) + B1*B3*pho2*x(4) - B1*B2*B3*x(3)^2 + B1*B2*B3*x(2)*x(3) - B1*B2*B3*x(2)*x(4) + B1*B2*B3*x(3)*x(4)))/(7*(B1*pho2*pho3 + B2*pho1*pho3 + B3*pho1*pho2 - B1*B2*pho3*x(2) + B1*B2*pho3*x(3) - B1*B3*pho2*x(3) - B2*B3*pho1*x(3) + B1*B3*pho2*x(4) + B2*B3*pho1*x(4) + A1*pho1*pho2*pho3 + A2*pho1*pho2*pho3 + A3*pho1*pho2*pho3 - B1*B2*B3*x(3)^2 + B1*B2*B3*x(2)*x(3) - B1*B2*B3*x(2)*x(4) + B1*B2*B3*x(3)*x(4) - A1*B2*pho1*pho3*x(2) + A1*B2*pho1*pho3*x(3) - A1*B3*pho1*pho2*x(3) + A1*B3*pho1*pho2*x(4) - A2*B3*pho1*pho2*x(3) + A2*B3*pho1*pho2*x(4) - A1*B2*B3*pho1*x(3)^2 + A1*B2*B3*pho1*x(2)*x(3) - A1*B2*B3*pho1*x(2)*x(4) + A1*B2*B3*pho1*x(3)*x(4))) + (2500*((13*alpha_i2*(T_r2 - x(6)))/10 - mdot_in*(x(2) - x(3)))*(B2*pho1*pho3 - B2*B3*pho1*x(3) + B2*B3*pho1*x(4)))/(7*(B1*pho2*pho3 + B2*pho1*pho3 + B3*pho1*pho2 - B1*B2*pho3*x(2) + B1*B2*pho3*x(3) - B1*B3*pho2*x(3)- B2*B3*pho1*x(3) + B1*B3*pho2*x(4) + B2*B3*pho1*x(4) + A1*pho1*pho2*pho3 + A2*pho1*pho2*pho3 + A3*pho1*pho2*pho3 - B1*B2*B3*x(3)^2 + B1*B2*B3*x(2)*x(3) - B1*B2*B3*x(2)*x(4) + B1*B2*B3*x(3)*x(4) - A1*B2*pho1*pho3*x(2) + A1*B2*pho1*pho3*x(3) - A1*B3*pho1*pho2*x(3) + A1*B3*pho1*pho2*x(4) - A2*B3*pho1*pho2*x(3) + A2*B3*pho1*pho2*x(4) - A1*B2*B3*pho1*x(3)^2 + A1*B2*B3*pho1*x(2)*x(3) - A1*B2*B3*pho1*x(2)*x(4) + A1*B2*B3*pho1*x(3)*x(4))) + (2500*B3*pho1*pho2*((13*alpha_i3*(T_r3 - x(7)))/10 - mdot_in*(x(3) - x(4))))/(7*(B1*pho2*pho3 + B2*pho1*pho3 + B3*pho1*pho2 - B1*B2*pho3*x(2) + B1*B2*pho3*x(3) - B1*B3*pho2*x(3) - B2*B3*pho1*x(3) + B1*B3*pho2*x(4) + B2*B3*pho1*x(4) + A1*pho1*pho2*pho3 + A2*pho1*pho2*pho3 + A3*pho1*pho2*pho3 - B1*B2*B3*x(3)^2 + B1*B2*B3*x(2)*x(3) - B1*B2*B3*x(2)*x(4) + B1*B2*B3*x(3)*x(4) - A1*B2*pho1*pho3*x(2) + A1*B2*pho1*pho3*x(3) - A1*B3*pho1*pho2*x(3) + A1*B3*pho1*pho2*x(4) - A2*B3*pho1*pho2*x(3) + A2*B3*pho1*pho2*x(4) - A1*B2*B3*pho1*x(3)^2 + A1*B2*B3*pho1*x(2)*x(3) - A1*B2*B3*pho1*x(2)*x(4) + A1*B2*B3*pho1*x(3)*x(4)));
dx(2)=  (2500*((13*alpha_i2*(T_r2 - x(6)))/10 - mdot_in*(x(2) - x(3)))*(B2*pho3 - B2*B3*x(3) + B2*B3*x(4)))/(7*(B1*pho2*pho3 + B2*pho1*pho3 + B3*pho1*pho2 - B1*B2*pho3*x(2) + B1*B2*pho3*x(3) - B1*B3*pho2*x(3) - B2*B3*pho1*x(3) + B1*B3*pho2*x(4) + B2*B3*pho1*x(4) + A1*pho1*pho2*pho3 + A2*pho1*pho2*pho3 + A3*pho1*pho2*pho3 - B1*B2*B3*x(3)^2 + B1*B2*B3*x(2)*x(3) - B1*B2*B3*x(2)*x(4) + B1*B2*B3*x(3)*x(4) - A1*B2*pho1*pho3*x(2) + A1*B2*pho1*pho3*x(3) - A1*B3*pho1*pho2*x(3) + A1*B3*pho1*pho2*x(4) - A2*B3*pho1*pho2*x(3) + A2*B3*pho1*pho2*x(4) - A1*B2*B3*pho1*x(3)^2 + A1*B2*B3*pho1*x(2)*x(3) - A1*B2*B3*pho1*x(2)*x(4) + A1*B2*B3*pho1*x(3)*x(4))) - (2500*((13*alpha_i1*(T_r1 - x(5)))/10 - mdot_in*(h_in - x(2)))*(B2*pho3 + B3*pho2 - B2*B3*x(3) + B2*B3*x(4) + A1*pho2*pho3 + A2*pho2*pho3 + A3*pho2*pho3 - A1*B2*pho3*x(2) + A1*B2*pho3*x(3) - A1*B3*pho2*x(3) + A1*B3*pho2*x(4) - A2*B3*pho2*x(3) + A2*B3*pho2*x(4) - A1*B2*B3*x(3)^2 + A1*B2*B3*x(2)*x(3) - A1*B2*B3*x(2)*x(4) + A1*B2*B3*x(3)*x(4)))/(7*(B1*pho2*pho3 + B2*pho1*pho3 + B3*pho1*pho2 - B1*B2*pho3*x(2) + B1*B2*pho3*x(3) - B1*B3*pho2*x(3) - B2*B3*pho1*x(3) + B1*B3*pho2*x(4) + B2*B3*pho1*x(4) + A1*pho1*pho2*pho3 + A2*pho1*pho2*pho3 + A3*pho1*pho2*pho3 - B1*B2*B3*x(3)^2 + B1*B2*B3*x(2)*x(3) - B1*B2*B3*x(2)*x(4) + B1*B2*B3*x(3)*x(4) - A1*B2*pho1*pho3*x(2) + A1*B2*pho1*pho3*x(3) - A1*B3*pho1*pho2*x(3) + A1*B3*pho1*pho2*x(4) - A2*B3*pho1*pho2*x(3) + A2*B3*pho1*pho2*x(4) - A1*B2*B3*pho1*x(3)^2 + A1*B2*B3*pho1*x(2)*x(3) - A1*B2*B3*pho1*x(2)*x(4) + A1*B2*B3*pho1*x(3)*x(4))) + (2500*B3*pho2*((13*alpha_i3*(T_r3 - x(7)))/10 - mdot_in*(x(3) - x(4))))/(7*(B1*pho2*pho3 + B2*pho1*pho3 + B3*pho1*pho2 - B1*B2*pho3*x(2) + B1*B2*pho3*x(3) - B1*B3*pho2*x(3) - B2*B3*pho1*x(3) + B1*B3*pho2*x(4) + B2*B3*pho1*x(4) + A1*pho1*pho2*pho3 + A2*pho1*pho2*pho3 + A3*pho1*pho2*pho3 - B1*B2*B3*x(3)^2 + B1*B2*B3*x(2)*x(3) - B1*B2*B3*x(2)*x(4) + B1*B2*B3*x(3)*x(4) - A1*B2*pho1*pho3*x(2) + A1*B2*pho1*pho3*x(3) - A1*B3*pho1*pho2*x(3) + A1*B3*pho1*pho2*x(4) - A2*B3*pho1*pho2*x(3) + A2*B3*pho1*pho2*x(4) - A1*B2*B3*pho1*x(3)^2 + A1*B2*B3*pho1*x(2)*x(3) - A1*B2*B3*pho1*x(2)*x(4) + A1*B2*B3*pho1*x(3)*x(4)));

不仅程序冗长，而且debug太麻烦！！！（主要是自己太笨，工作量太大），没其他好法子，所以希望大家给些好的方法，自己对ode45很多用法不太了解，谢谢大家了。

回复此楼