Implement changes suggested by Mauricio.

[ketch]

See #200.

[rjleveque]

I think in Approximate_solvers we need to replace \wave with {\matcal W} and \apdq with {\cal A}^+ since the macros aren't found (are they supposed to be)? Elsewhere these are written out explicitly.

I don't know what's going on with travis, but the tests seem to pass.

[ketch]

I think in Approximate_solvers we need to replace \wave with {\matcal W} and \apdq with {\cal A}^+ since the macros aren't found (are they supposed to be)? Elsewhere these are written out explicitly.

I made this work earlier with a plugin, but it's not worth it at this point. So I made these changes, except I used \cal because \mathcal didn't work.

[rjleveque]

Grepping mathcal it seems to be used in other notebooks such as Shallow_water_approximate and seems to work fine. (But note I misspelled it in my comment above, so if you copied and pasted, matcal wouldn't work.)

But the resulting rendered version seems to be the same with either one, so I don't think it matters.

[ketch]

if you copied and pasted

LOL, yes, I did exactly that. Must not have been thinking too clearly at the time...