IRR

IRR(values() [,guess])

Returns the interest rate for a series of unequal cash flows at regular intervals (implicit reinvestment rate) (Double).

values()	The array of cash flow values (Double).
guess	(Optional) The estimate to the value returned by this function (Double).

REMARKS

* The internal rate of return is the interest rate received for an investment consisting of payments and receipts that occur at regular intervals.
* The first value in the "values()" array must be negative.
* The "values()" must contain at least one negative value (a payment) and one positive number (a receipt).
* If "guess" is left blank, then 0.1 (10%) is used.
* It is important to ensure that the values in your array are in the correct order.
* This function uses iteration in it calculation and if the function cannot find a result after 20 tries, to within 0.001% it fails.
* You can use the MIRR function to return the interest rate for a series of unequal cash flows at regular intervals (explicit reinvestment rate).
* You can use the RATE function to return the interest rate for a series of equal cash flows at regular intervals.
* The equivalent Excel function is Application.WorksheetFunction.IRR
* The equivalent .NET function is Microsoft.VisualBasic.Financial.Irr
* For the Microsoft documentation refer to learn.microsoft.com

Dim ardoubles(3) as Double 
ardoubles(0) = -20 
ardoubles(1) = 10 
ardoubles(2) = 10 
ardoubles(3) = 20 
Debug.Print Irr(ardoubles)   '= 0.38367