Question: Delay Differential Equations and Dsolve

May 17 2014 Julesp 35
1

Hello,
I'm working on coupled differential equation.
The first system is : 
y1''+y1'+y1=q1
q1''+e(q12-1)q1'+q1=y1"

And the second one : 
y2''+y2'+y2=q2
q2''(t)+e(q22-1)q2'(t)+q2(t) = y2"+f(P) q1(t-tau)

This is a parametric system, f(P) and tau(P) are given function of the parameters P.
e is a constant

I have solved the first system with dsolve (using numeric option).
But when I try to solve the second one (with dsolve, numeric, setting P as a parameter), maple returns an error : 

"Error, (in dsolve/numeric/process_input) input system must be an ODE system, got independent variables {t, t-1}"

I think Maple doesn't like " q1(t-tau)".
I have tried to create a new function q where :
q(t)=q1(t-tau)
But Maple returns the same error.

How can I fix it ?

Thanks for reading

EDIT : I have read there is no function in maple that solve delay differential equation.
But this is not a true DDE because q2 has no effect on q1
So I hope there is a way to "fool" maple and still use dsolve.

EDIT 2 :
I have found how to make it works.
I was using dsolve with the option compile (which increase (a lot) the efficiency of computation).
I delete this option and that's working.
Nevertheless, without the option compile, the computation is very very slow.
MapleHelp recommands to combine the 2 systems for more efficiency. But, when I combine, maple return the previous error.
How can I make it quicker ?

Here is the code : 

test_2_cylindre_sans_compile.mw 

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