Solve 2nd order ordinary differential equations (Runge Kutta)

I have a second order differential equation which I need to solve, and plot the first 6 seconds of x(t). I wanted to use the Runge Kutta method but I'm struGgling to get my head around how to do it. Here's my equation:

d2xdt2=100*sin(8*pi*t)-(100*x)-2*dxdt

x(0) = 0

dxdt(0) = 0

I've tried using ode45 but I'm not sure how to define the function, ideally I want to use a manual method, ie recreate the Runge Kutta algorithm in MATLAB.

Any help is appreciated

Thanks

[Torsten]

Look at the example

"Solve Nonstiff Equation"

under

https://de.mathworks.com/help/matlab/ref/ode45.html

on how to rewrite your equation and apply ODE45 to solve it.