MATLABode求解器:无法满足集成公差 [英] MATLAB- ode solver: Unable to meet integration tolerances

问题描述

我在MATLAB中的 ode求解器遇到了问题.我使用了所有ode求解器，例如ode23s，ode23，ode15s，ode45等.而且由于警告错误，我的代码无法计算:

I have a problem with ode solver in MATLAB. I used all ode solver like ode23s, ode23, ode15s, ode45 and so on. And my code can not be calculated, because of error-warning:

警告:在t = 8.190397e + 01时失败.无法满足整合 公差不降低步长小于最小值 在时间t允许(2.273737e-13).

Warning: Failure at t=8.190397e+01. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (2.273737e-13) at time t.

我想计算它，请直接在我的代码中帮助我.谢谢.

I would like to calculate it, please help me directly in my code. Thank you.

第一个脚本:

% floq.m
global c_alpha c_beta c_gama om ms ks bs mii

 % Parameters            
   c_alpha=1;
   c_beta=1.1;
   c_gama=1.1;  
   ms=1;                             
   ks=1;                                                       
   D=0.01;
   OM=sqrt(ks/ms);                     
   bs=2*D*ms*OM;                       

 % Solver    
   sourad = 0.1:0.13:10;
   for pom = 1:length(sourad)
       eta= sqrt(1/sourad(pom));
       om=eta*OM;                          
       T=2*pi/(eta*OM);    

       for mii=-10*(eta^2):0.13:10*(eta^2)  
           tspan=0:0.01:T;
           [tt,x1]=ode23(@fun,tspan,[1; 0]);    
       end
   end       

第二个脚本=功能:

% fun.m

 function v=fun(tt,x1);
 global c_alpha c_beta c_gama om ms ks bs mii

 mt=ms*cos(om*tt);
 bt=bs*cos(2*om*tt);
 kt=ks*cos(2*om*tt);

 % Matrix A
 A=[(-bs+mii*c_beta*bt)/(ms-mii*c_gama*mt) (-ks+mii*c_alpha*kt)/(ms-mii*c_gama*mt); 1 0];

 % Method
 v=A*x1;

谢谢.

推荐答案

您正在通过ODE函数的一个极点进行集成.在极点，所有解决方案都结束了.极点左右的轨迹不能合并成一个更大的轨迹.

You are integrating over a pole of the ODE function. At the pole, every solution ends. Trajectories to the left and right of the pole can not joined into one larger trajectory.

极点是1 = mii*c_gama*cos(om*t)的第一个正解t.如果mii*c_gama >= 1总是有这样的解决方案.

The pole is the first positive solution t of 1 = mii*c_gama*cos(om*t). If mii*c_gama >= 1 there is always such a solution.

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