Hi!

I want to plot some functions that I defined for my models.

I did the following but there is probably a better way:

```
#!/usr/bin/env python3
import matplotlib.pyplot as plt
from brian2 import run, NeuronGroup, StateMonitor, defaultclock
from brian2 import second
group = NeuronGroup(1, "x = (t/second - 100)**2 : 1", method='euler')
statemon = StateMonitor(group, ['x'], record=True)
defaultclock.dt = 0.1*second
run(200*second)
plt.plot(statemon.t/second-100, statemon.x[0])
plt.xlabel('x')
plt.ylabel('x*x')
plt.savefig("brian_plotting.png")
```

Can you please point me to the correct way to plot equations used in Brian2?

Thanks in advance,

Sebastian