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Topic: how to Solve coupled ODEs
Replies: 5   Last Post: Feb 12, 2013 11:07 AM

 Messages: [ Previous | Next ]
 Torsten Posts: 1,717 Registered: 11/8/10
Re: (yet unsolved) how to Solve coupled ODEs
Posted: Feb 12, 2013 11:07 AM

"Henry" wrote in message <kfb8m3\$mom\$1@newscl01ah.mathworks.com>...
> Problem not yet solves, any helps please?

Just compare line for line:

global a b c d e
a=...;
b=...;
c=...;
d=...;
e=...;
[t,y] = ode45(@odeeqns, [0 3], [1 1]);

function dyds = odeeqns(s,y)
global a b c d e
dyds = zeros(2,1)
dyds(1,1) = 1/y(1) *(y(2)*(d+s /y(2))-a *y(1)*sqrt(y(1)^2+(e+y(2))^2));
dyds(2,1) = -(y(2)*(b+y(2))*sqrt(y(1)^2+(e+y(2))^2))/y(1)-y(2)/s - c;

Best wishes
Torsten.

If you start with s=0 as I suggested in the call to ode45, you will get problems in the evaluation of dyds(2,1) because of the term y(2)/s (division by zero).
Please supply the values of the parameters a,b,c,d and e, the interval of integration and the error message you received.

Best wishes
Torsten.

Date Subject Author
2/7/13 Torsten
2/8/13 Torsten
2/12/13 Torsten