Should OffHilbert/OffSingularIntegral store concrete data in low-rank form?

[MikaelSlevinsky]

Banded linear algebra is arguably inapplicable to these operators, setting them on the path to being amenable to hierarchical solvers.

Should we also combine them with Hilbert/SingularIntegral and have them generated by a variation of the @calculus_operator macro?

[dlfivefifty]

There's a lot to be done with improving large bandwidth linear algebra. I think when the bandwidth is large,creating a dense matrix and using LAPack is much faster than ApproxFun's \