Evaluates the net present value of a stream of unequal periodic cash flows, which are subject to a given discount rate.

rate—Interest rate per period.

values—One-dimensional array of equally-spaced cash flows.

result—The net present value of an investment. If no result can be computed, NaN is returned.

Double—If present and nonzero, double precision is used.

Function NET_PRES_VALUE computes the net present value of an investment. Net present value is the current value of a stream of payments, after discounting the payments using some interest rate.

It is found by solving the following with count = N_ELEMENTS (values):

where valuei = the ith cash flow.

In this example, NET_PRES_VALUE computes the net present value of a $10 million prize paid in 20 years ($500,000 per year) with an annual interest rate of 6%.

rate = 0.06

value = FLTARR(20)

value(*) = 500000.

PRINT, NET_PRES_VALUE(rate, value)

; PV-WAVE prints: 5.73496e+06