What is Runge-kutta: Definition and 67 Discussions

In numerical analysis, the Runge–Kutta methods (English: (listen) RUUNG-ə-KUUT-tah) are a family of implicit and explicit iterative methods, which include the well-known routine called the Euler Method, used in temporal discretization for the approximate solutions of ordinary differential equations. These methods were developed around 1900 by the German mathematicians Carl Runge and Wilhelm Kutta.

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  1. M

    Problems with Runge-Kutta method

    Hi everyone, I've a little problem with my algorithm. I have two grids: one for time and the other one for the radius. I need to evaluate this equation: \frac{d\beta(r,t)}{dt}=A\beta(r,t)^N I try solving this with a simple Runge Kutta II method, but I'm not convinced at all that this works...
  2. I

    Matlab Problem: Runge-Kutta Fehlberg

    Homework Statement I need to write a Matlab program that solves the following: Use the Runge-Kutta Fehlberg Algorithm with tolerance TOL= 10^(-4) to approximate the solution to the initial-value problem: y'=(y/t)^2 + y/t, 1<=t<=1.2, y(1)=1, with hmax=0.05 and hmin=0.02. Homework...
  3. P

    2nd Order Runge-Kutta: 2nd Order Coupled Differential Equations

    Homework Statement Consider the system of coupled second-order differential equations u''-(t+1)(u')^2+2uv-u^3=\cos{t} 2v''+(\sin{t})u'v'-6u=2t+3 with initial conditions u(0)=1, u'(0)=2, v(0)=3, v'(0)=4. Use the second order Runge-Kutta method with h=0.2 and a=2/3, b=1/3, \alpha=\beta=3/2...
  4. I

    Runge-Kutta Numerical Integration

    Homework Statement In brief, I am working on a stellar model. We started with these four equations: \delta q/\delta x = px^{2}/t \delta p /\delta x = -pq/tx^{2} \delta t /\deltax = -Cp^{1.75} / x^{2}t^{8325} \delta t /\delta x = -2q/5x^{2} In the model you switch to the 4th...
  5. S

    Fourth Order Runge-Kutta Method

    Hi As a high school student I was working on an independent project and at last I found final differential equations that I want to integrate them numerically. I read a little bit and found out that Fourth Order Runge-Kutta Method is one of the good methods. By the way could you please help me...
  6. P

    Having a hard time understanding Runge-Kutta integration method

    Greetings, As I am in vacation now there is no way to ask my teacher so I will resort to this forum, I searched and didn't find it on the forum ( hope I haven't skipped anything ) so here goes my question: For the Runge-Kutta integration methods, I am really puzzled as to what the 'f'...
  7. T

    Reducing third order ODE to a system of first order equs + 4th order runge-kutta

    Hi, I am stuck on the initial steps of this problem - its been a while since my diff. eq course. I need to reduce this into a system of three equations then apply a 4th order runge kutta method to solve. Homework Statement f'''+f*f''=0 Boundary conditions: f'(0)=f(0)=0 f'(infinity)=0 A...
  8. K

    Solving 4th Order Runge-Kutta w/ dy/dt = y, y(0)=1

    Homework Statement Use the fourth order Runge-Kutta formula to advance the differential equation: dy/dt = y with y(0)=1 forward one step h. That is find y(h). Homework Equations The Attempt at a Solution The Runge-Kutta formula is: x(i+1)=x(i)+h/6 [k(1)+2k(2)+2k(3)+k(4)]...
  9. W

    Backward Runge-Kutta Method (4th Order)

    Homework Statement Hi, As part of a computing project I'm doing, I need to use a shooting method, to solve a set of differential equations. I have some trial boundary conditions at either end of the equations, and am going to be integrating from each end and varying some parameters until...
  10. C

    Is It Runge-Kutta or Runge-Kutter?

    I'm familiar with the Runge-Kutta methods for solving ODEs, but recently I've come across a reference to "Runge-Kutter", in which it appears to be used synonamously (unfortunately it's just a reference, the method is not stated explicitly). Is this a common typo, or is there a separate Runge...
  11. A

    Download "Control theoretic techniques" Runge-Kutta Paper (1991) Free

    I'm trying to find a location in the Internet where I can download (for free) the following paper: Kjell Gustafsson , "Control theoretic techniques for stepsize selection in explicit Runge-Kutta methods" (Year of Publication: 1991 ) Thanks in advance :cool:
  12. M

    Runge-Kutta vs Euler: Solving Two-Dimensional Differential Equation

    Hi, I don't know if this is the right forum to adress, but I will try nevertheless Im solving a simple two-dimensional differential equation: dx/dt = (-y,x) which will give a circle when integrating over time. Now, the problem is that the simple euler scheme seems to be a lot more...
  13. F

    Does Anyone Have a C++ or Fortran90 Code for 4th Order Runge-Kutta Method?

    please i'll like to ask if someone have a code written in c++ or in foltran90 on 4th order runge-kutta method of numerical computation. thanks
  14. D

    Results same w/ Euler, Improved Euler, & Runge-Kutta

    I've been trying to do some simulations using the Euler, improved Euler, and Runge-Kutta methods. My results for the improved Euler and Runge-Kutta are very close to my results with the plain old Euler method. If there is any improvement, it is negligible. This lack of improvement surprises...
  15. S

    How to Apply Runge-Kutta to Solve a Simple Motion Problem

    Hi, Could someone please show me how to solve the following simple problem using the Runge-Kutta (RK4) integration method? A car at t=0 has acceleration 10m/s/s, velocity 0m/s. How far would the car travel in 10 seconds? I know this can be solved using the equations of motion (giving...
  16. G

    Classical mechanics & runge-kutta

    We have a pendullum in a car, that is being pulled with: a) constant F force b) connectec to a spring, with force F = -kx The physics part is done, and we have 2 differential equations (non-lineer), and we're supposed to write a C program to calculate theta(t) and x(t) from them. We should...
  17. P

    C/C++ How Can I Fix My C++ Runge-Kutta Method to Correctly Update Y Values?

    Hi guys. I was wondering if anyone could help me with this code. I have sucessfully created a program in visual basic that can run a runge-kutta method. However I want to create one in c++, maybe eventually turn it into a .dll when i work out how to create and use them. :smile: Here is...
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