solving many linear differential equations through ODE solver.

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P K 2019-1-6

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https://ww2.mathworks.cn/matlabcentral/answers/438438-solving-many-linear-differential-equations-through-ode-solver

评论： P K 2019-1-17

采纳的回答： Torsten

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I am not sure whether my approach is good or not, because my simulation takes ENORMOUS amount of time in execution.

I have a general form of differential equations , which contain summation signs, and it is suumed over i,j. When i,j varies, the number of variables in the differential equations also changed. Index i and j are related with a relation.That means the number of variable are also dependent on i & j .So, here is what i am planning

syms H(i,j) % generalized variable
% Storing the varaibles
n=10 %number of variables (This would change)
 for i=1:n
         for j=1:n
             if i+j==... && i/2==...
              T(i,j)=H(i,j) % Store the variable              
         end
 end
%% Now i am using T as variable, and using 4 "for loops" to form the differential equations.
% Then solve it through ODE .

The code is working for small value of "n". But it takes 3 days when n=50. And runs out of memory when n=60. How can i optimize my code and avoid syms ? I can observe, that the major problem is in creating the equations.Am i doing wrong in creating the variables like this ? Is there any way to overcome this ?