Converting ODE to a system of ODEs

In summary, we have a given ODE $x''-x+x^3+\gamma x' = 0$ and we can rewrite it as a linear system with $x_1 = x$ and $x_2 = x'$, giving us the equations $x_1' = x_2$ and $x_2' = x_1 - x_1^3 + \gamma x_2$. We have a typo in the second equation which should be $x_2' = x_1 - x_1^3 - \gamma x_2$. We are also looking for the attraction basin for this system, as discussed in another post on the Math Help Boards.
  • #1
Dustinsfl
2,281
5
Given $x''-x+x^3+\gamma x' = 0$.

Is the below correct? Can I do this? The answer is yes.

Let $x_1 = x$ and $x_2 = x'$. Then $x_1' = x_2$.
\begin{alignat}{3}
x_1' & = & x_2\\
x_2' & = & x_1 - x_1^3 + \gamma x_2
\end{alignat}

Then I have the above linear system from the given ODE.
 
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  • #2
dwsmith said:
Given $x''-x+x^3+\gamma x' = 0$.

Is the below correct? Can I do this? The answer is yes.

Let $x_1 = x$ and $x_2 = x'$. Then $x_1' = x_2$.
\begin{alignat}{3}
x_1' & = & x_2\\
x_2' & = & x_1 - x_1^3 + \gamma x_2
\end{alignat}

Then I have the above linear system from the given ODE.

Second equation should be
$$x_{2}'=x_{1}-x_{1}^{3}-\gamma x_{2}.$$
 
  • #3
Ackbach said:
Second equation should be
$$x_{2}'=x_{1}-x_{1}^{3}-\gamma x_{2}.$$

Thanks typo. I trying to find the attraction basin for this system in another post. Are you familiar with that stuff?
 
  • #4
dwsmith said:
Thanks typo. I trying to find the attraction basin for this system in another post. Are you familiar with that stuff?

I think your question is answered http://www.mathhelpboards.com/f17/damping-coefficient-2045/.
 
  • #5


Yes, your approach is correct. Converting a single second-order ODE into a system of first-order ODEs is a common technique in solving differential equations. By defining $x_1 = x$ and $x_2 = x'$, you have effectively created a system of two first-order ODEs, which can be solved using standard methods. Your resulting linear system is also correct.
 

1. What is an ODE?

An ODE, or ordinary differential equation, is a mathematical equation that describes how a function changes over time. It involves the function itself, its derivatives, and the independent variable.

2. Why do we need to convert ODEs to a system of ODEs?

Converting ODEs to a system of ODEs allows us to solve for multiple unknown functions simultaneously. This is useful in many scientific fields, such as physics, engineering, and biology, where multiple variables are interrelated and must be studied together.

3. How do you convert a single ODE to a system of ODEs?

To convert a single ODE to a system of ODEs, we first identify the dependent variables (functions) and their derivatives. Then, we write each derivative as a function of the dependent variables and the independent variable. Finally, we use these equations to create a system of equations that can be solved simultaneously.

4. What are some advantages of using a system of ODEs over a single ODE?

A system of ODEs allows us to study multiple variables and their interactions, giving us a more comprehensive understanding of the system. It also allows for more accurate predictions and simulations, as real-world systems often involve more than one variable.

5. Can all ODEs be converted to a system of ODEs?

No, not all ODEs can be converted to a system of ODEs. This conversion is only possible when there are multiple dependent variables that are interrelated. If there is only one dependent variable, then it can be solved using a single ODE. Additionally, some ODEs may be too complex to convert to a system of ODEs, and it may be more efficient to solve them using other methods.

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