Thanks to Andrej, I've updated file_search_mac to include
contrib/integration.
The packages pw and abs_integrate overlap, but abs_integrate doesn't
do everything pw does. I have no plans to extend abs_integrate to
support piecewise defined functions.
One difference between pw and abs_integrate (I'd guess) is that they
have disjoint bug lists :) I don't know of any bugs in pw, but do know
of bugs in abs_integrate--I already patched one :(
Barton