Can Euler Forward or 4th Order Runge-Kutta Methods Approximate Systems of ODEs?

In summary, the question is about using Euler Forward or 4th order Runge-Kutta Methods to approximate a system of differential equations that is not in the normal form. The speaker mentions that they are familiar with using these methods for the normal form and that it is possible to solve such equations using linear algebra. However, they are unsure about how to determine the stability criterion for the timestep when the system is not in the normal form. The speaker also mentions the importance of considering initial values when approximating the system.
  • #1
worryingchem
41
1
My question is about whether it's possible to use the Euler Forward or 4th order Runge-Kutta Methods to approximate the following system ( where the differential of other equations are on the right hand side) :
$$
\begin{cases}
\frac{dy_1}{dt} = f_1(y_1,y_2,y'_2, ... , y_n, y'_n, t) \\
\frac{dy_2}{dt} = f_2(y_1,y'_1,y_2, ... , y_n, y'_n, t) \\
...\\
\frac{dy_n}{dt} = f_n(y_1,y'_1, ... , y_{n-1}, y'_{n-1}, y_n, t) \\
\end{cases}
$$
I know you can do it for the normal form: ## \frac{d^{(n)}y}{dt^{(n)}} = f(y, y', y'', ... , y^{(n)}, t) ## and it's also possible to analytically solve differential equations of that form using linear algebra, but I'm not sure when it's not in the normal form.
 
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  • #2
Yes, you can use those schemes because you know and use all the quantities at the right hand side at timestep 't'. However, it will be difficult to determine the stability criterion for the timestep to use a priori.
 
  • #3
Thank you, I forgot about the initial values used to approximate this.
 

1. What is a system of ODE's?

A system of ODE's (ordinary differential equations) is a set of equations that describe how a set of variables change over time. It is used to model dynamic systems in various fields such as physics, biology, and engineering.

2. Why do we need to approximate a system of ODE's?

In most cases, it is not possible to find an exact analytical solution to a system of ODE's. Therefore, we need to approximate the solution using numerical methods to get an accurate estimate of the behavior of the system.

3. What are some common numerical methods used for approximating a system of ODE's?

Some commonly used numerical methods for approximating a system of ODE's include Euler's method, Runge-Kutta methods, and the finite difference method. Each method has its own advantages and limitations, and the choice of method depends on the specific problem at hand.

4. How accurate are the approximations of a system of ODE's?

The accuracy of the approximations depends on several factors such as the method used, the step size used in the approximation, and the complexity of the system. In general, the accuracy increases as the step size decreases, but this also increases the computational time.

5. Can approximating a system of ODE's be used for real-world applications?

Yes, approximating a system of ODE's is widely used in various real-world applications. It is especially useful for modeling complex systems where analytical solutions are not feasible. Applications include predicting the weather, designing control systems for vehicles, and studying population dynamics.

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