solving coupled differential equations.

i need help to solve the couple differential equation of the following type

Answer 1

[Torsten]

Use one of the solvers from the ODE-suite to solve:

https://de.mathworks.com/help/matlab/math/choose-an-ode-solver.html

Best wishes

Torsten.

[imran saeed]

i use ode45 to solve i can solve for small number of equations. but i need to solve at least 50 coupled equations. system of equations is as follow can you give some guidance. i can solve simple equations using ode45 but this is very complicated.

[Torsten]

function dz = fun(t,z)
x=z(1:50);
y=z(51:100);
dx=zeros(50,1);
dy=zeros(50,1);
for i=1:50
  for j=1:50
   if j==i
     continue
   end
   dx(i)=dx(i)+((y(i)-y(j))^2-(x(i)-x(j))^2)/((y(i)-y(j)^2+(x(i)-x(j))^2)^2;
   dy(i)=dy(i)+(y(i)-y(j))*(x(i)-x(j))/((y(i)-y(j))^2+((x(i)-x(j))^2))^2;
  end
end 
dz=[dx;dy];

Best wishes

Torsten.

[imran saeed]

thank you very much for your help

[imran saeed]

it worked beautifully