Runge–Kutta method

This online calculator implements the Runge-Kutta method, a fourth-order numerical method to solve the first-degree differential equation with a given initial value.

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Created: 2019-09-22 14:23:29, Last updated: 2020-11-28 11:36:56
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This content is licensed under Creative Commons Attribution/Share-Alike License 3.0 (Unported). That means you may freely redistribute or modify this content under the same license conditions and must attribute the original author by placing a hyperlink from your site to this work https://planetcalc.com/8400/. Also, please do not modify any references to the original work (if any) contained in this content.

You can use this calculator to solve first-degree differential equation with a given initial value using the Runge-Kutta method AKA classic Runge-Kutta method (because there is a family of Runge-Kutta methods) or RK4 (because it is a fourth-order method).

To use this method, you should have differential equation in the form
y \prime = f(x,y)
and enter the right side of the equation f(x,y) in the y' field below.

You also need initial value as
y(x_0)=y_0
and the point x for which you want to approximate the y value.

The last parameter of a method - a step size, is a step to compute the next approximation of a function curve.

Method details can be found below the calculator.

PLANETCALC, Runge–Kutta method

Runge–Kutta method

Digits after the decimal point: 2
Differential equation
 
Approximate value of y
 
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The Runge-Kutta method

Just like Euler method and Midpoint method, the Runge-Kutta method is a numerical method that starts from an initial point and then takes a short step forward to find the next solution point.

The formula to compute the next point is
y_{n+1}=y_n+\frac{1}{6}(k_1+2k_2+2k_3+k_4) \\ x_{n+1}=x_n+h

where h is step size and

k_1=hf(x_n,y_n) \\ k_2=hf(x_n+\frac{h}{2}, y_n+\frac{k_1}{2}) \\ k_3=hf(x_n+\frac{h}{2}, y_n+\frac{k_2}{2}) \\ k_4=hf(x_n+h, y_n+k_3)

The local truncation error of RK4 is of order O\left(h^5\right), giving a global truncation error of order O\left(h^4\right).

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PLANETCALC, Runge–Kutta method

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