Plot phase portraits of 2D differential equations using Python's `matplotlib`

and `scipy`

libraries.

Inspired by Maxima's `plotdf`

function.

## Usage

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)`

.

## Dependencies

Both Python 2 and 3 are supported. You need `matplotlib`

, `numpy`

and `scipy`

installed.

## Installation

The package is on PyPI so you can install it with

```
$ pip install plotdf
```