# Question:solve syst ODEs

## Question:solve syst ODEs

Maple

Hello every body,  and many thanks for our help !!!

I have two questions :

First, I have a system of 2 ODE of second order. To solve it I looked in the forum and found this program:

restart;
with(plots):

M[1] := 50; M[2] := 30; L[1] := 100; L[2] := 80; S[1] := (1/2)*L[1]; S[2] := (1/2)*L[2]; e[1] := 5; e[2] := 15; g := 9.81; K[1] := 100; K[2] := 100;

ode1 := (1/2)*M[2]*(2*L[1]*(diff(Theta[1](t), t, t))*S[2]+2*S[2]^2*(diff(Theta[2](t), t, t))+2*e[2]^2*(diff(Theta[2](t), t, t)))-(1/2)*M[1]*g*S[1]*Theta[1]^2+K[1]*Theta[1]^2=0;
ode2 := M[1]*(diff(Theta[1](t), t, t))*(S[1]^2+e[1]^2)+(1/2)*M[2]*(2*L[1]^2*(diff(Theta[1](t), t, t))+2*L[1]*S[2]*(diff(Theta[2](t), t, t)))-(1/2)*M[2]*g*L[1]*Theta[1]^2-(1/2)*M[2]*g*S[2]*Theta[2]^2+K[2]*Theta[2]^2-2*K[2]*Theta[2]*Theta[1]+K[2]*Theta[1]^2=0;

ic1 := Theta[1](0) = 20, Theta[2](0) = 0;
ic2 := diff(Theta[1](0), t) = 0, diff(Theta[2](0), t) = 0;

sys := {ic1, ic2, ode1, ode2};
sol := dsolve(sys, numeric, output = listprocedure);
plots[odeplot](sol,[t,Theta[1](t)],0..60);

however it doen't work and I don't know why. It looks to have a problem 0=0 .

Second question:

If in two differents maple-file I have one equation.

How to call them into a third one? ( to avoid to copy 2 big programs and just take the result). A few years ago, I did something like this but I am unable to remember. I look in the help for call and callback. It doesn't look to be what i look for.

Thanks a lot,
Pierre

﻿