next up previous contents
Next: Creating a template file Up: A generalised Runge-Kutta subroutine Previous: Hamiltonian systems

The gravitational n-body problem

For the classical n-body problem in dynamics [2], the Hamiltonian is of potential or separable form:

\begin{displaymath}
H({\bf q},{\bf p})=T({\bf p}) + V({\bf q})\end{displaymath}

with

\begin{displaymath}
T({\bf p}) = {{\bf p}.{\bf p}\over 2} \quad , \quad
 V({\bf q}) = {1\over \sqrt{{\bf q}.{\bf q}}}\end{displaymath}

where ${\bf x}.{\bf x}$ denotes the scalar product of ${\bf x}$.For example, in 2 degrees of freedom,

\begin{displaymath}
H({\bf q},{\bf p})~= ({p_1}^2~+~{p_2}^2)/2 +
1/{\sqrt{({q_1}^2~+~{q_2}^2)}}\end{displaymath}

where subscripts denote vector components.



Jorge Romao
5/14/1998