functions available for use with aggregate?

What are the functions available for use with ?aggregate??  Where can a reference to them be found?

 

Since aggregate is a S3 generic, you can use

methods(aggregate)

to see what objects have an "aggregate" method. For me, I have the 
following:

 > methods(aggregate)
[1] aggregate.data.frame aggregate.default    aggregate.frm*
[4] aggregate.ts

    Non-visible functions are asterisked
 >

See ?methods for more details.

HTH,

--sundar