# XNpv(rate, values,dates,I)

Computes the net present value (NPV) of a non-periodic cash flow with constant discount rate. The rate parameter is the annual discount rate for a 365 day year. The values parameter is indexed by I and contains the cash flow amounts, with positive values indicating inflows (payments received) and negative values indicating outflows (payments made). The dates parameter must also be indexed by I and contains the date in which each payment is made. The date is expressed as the number of days since the date origin (e.g., Jan 4, 1904).

For periodic cash flows, the Npv function can be used without having to specify the actual dates of each payment. The page on Npv discusses the concept of net present value in some detail.

# Examples

A treasury note with a coupon rate of 5.5% is being offered on the second-hand market for \$102.32 on 10 Nov 2008. The note matures on 15 May 2009, and its next coupon payment occurs on 15 Nov 2008. Calculate its yield-to-maturity.

If we purchase this on 10 Nov 2008, our cash flow for this note is given by the following schedule:

cfDate cfAmount
10 Nov 2008 -\$102.32
15 Nov 2008 \$2.75
15 May 2009 \$102.75

The yield to maturity is given by:

Irr(cfAmount,cfDate,cfDate) → 6.36%