The IAggregateFunction type exposes the following members.
Accumulates the passed values in the aggregate.
Gets the value that the aggregate instance keeps currently accumulated.
Initializes the aggregate function instance. Implement to set the aggregate in its initial state ready to accumulate and merge values.
Merges another instance of the same aggregate function into the current instance. Implement this method to allow the reporting engine to merge the two resulting aggregates coming from two subsets of the aggregated data source rows.