pyrk 0.5.2

A simple runge-kutta 4 integrator

A simple implementation of Runge-Kutta for python.

Install from PyPi

pip install pyrk

Develop

pip install -e .

Usage

See the examples in the docs folder or a simple one:

from __future__ import division, print_function
from pyrk import RK4
import numpy as np
import matplotlib.pyplot as plt

def vanderpol(t, xi, u):
        dx, x = xi
        mu = 4.0 # damping

        ddx = mu*(1-x**2)*dx-x
        dx = dx

        return np.array([ddx, dx])

rk = RK4(vanderpol)
t, y = rk.solve(np.array([0, 1]), .01, 200)

y1 = []
y2 = []
for v in y:
        y1.append(v[0])
        y2.append(v[1])

plt.plot(y1, y2)
plt.ylabel('velocity')
plt.xlabel('position')
plt.grid(True)
plt.show()