Plot phase portraits of 2D differential equations using
Python's matplotlib and scipy libraries.
Inspired by Maxima's plotdf function.
To plot dx/dt = y, dy/dt = -g sin(x) / l - b y/ (m l):
from math import sin
from plotdf import plotdf
def f(x,g=1,l=1,m=1,b=1):
return np.array([x[1],-g*sin(x[0])/l-b*x[1]/m/l])
plotdf(f, # Function giving the rhs of the diff. eq. system
np.array([-10,2]), # [xmin,xmax]
np.array([-14,14]),# [ymin,ymax]
[(1.05,-9),(0,5)], # list of initial values for trajectories (optional)
# Additional parameters for `f` (optional)
parameters={"g":9.8,"l":0.5,"m":0.3,"b":0.05})
For the full list of parameters to plotdf, see help(plotdf.plotdf).
Both Python 2 and 3 are supported. You need matplotlib,
numpy and scipy installed.
The package is on PyPI so you can install it with
$ pip install plotdf