Broken page for PyClaw

[rjleveque]

@ketch: I noticed that at least one page in the PyClaw docs are broken,
http://www.clawpack.org/pyclaw/intro_notebook.html

I haven't gone through others recently.

That page seems to be built from a notebook and when I tried running the notebook I got other errors since np isn't imported,

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-7-89e22e0027eb> in <module>()
      1 x=domain.grid.x.centers
      2 bet=100; gam=5; x0=0.75
----> 3 claw.solution.q[0,:] = np.exp(-bet * (x-x0)**2) * np.cos(gam * (x - x0))
      4 claw.solution.q[1,:] = 0.
      5 

NameError: name 'np' is not defined