The first variable is the account in which the initial cash outlay exists at in a period.

The second variable is the cash stream beginning in a period.

The percentage is an optional guess at the IRR.

The internal rate of return of a stream of cash flows.

A project with an initial invest in 2000 and a cash flow beginning in 2000, uses this formula:

@irr(v300(1999), v4100(2000))

if the initial investment exists in v300 of 1999. The cash stream comes from the cash flow of Operations (v4100) beginning in 2000.