• Matplotlib version: 2.0.0b4+1.g4e507ae, Python version: 3.5.2 and Platform: Ubuntu 16.04 64bit
• Matplotlib from source and Python is shipped with system
• If you run the code either within "ipython3 --pylab" or within a cli, the ax.autoscale() fuction does not work. But strangely, it works inside jupyter or just change "add_axes" to "add_subplot".

import matplotlib as mpl
import matplotlib.pyplot as plt
fig = plt.figure()
xmin=0
xmax=1.6
ymin=0
ymax=1.6
ax = fig.add_axes([xmin,ymin,xmax-xmin,ymax-ymin])
#ax=fig.add_subplot(111)
l=mpl.lines.Line2D([xmin,xmax],[(ymin+ymax)/2,(ymin+ymax)/2])
ax.add_line(l)
ax.autoscale()
print(type(ax))
plt.show()

From "ipython3 -pylab"

from "jupyter notebook"