**rk4_test**,
a MATLAB code which
calls rk4(), which
implements a simple Runge-Kutta solver for an initial value problem.

rk4, a MATLAB code which applies the fourth order Runge-Kutta (RK) algorithm to estimate the solution of an ordinary differential equation (ODE) at the next time step.

- rk4_test.m, calls all the tests.
- rk4_test.sh, runs all the tests.
- rk4_test.txt, the output file.

- rk4_predator_test.m, tests rk4 on a predator-prey system.
- predator_deriv.m, the right hand side of the predator-prey system.
- rk4_predator_plot.png, the time plot.
- rk4_predator_phase.png, the phase plot.