Cash Flows
x=. 20 25 30 30 NB. payments
y=. 0.05 0.05 0.06 0.06 NB. interest rates
NB. present value, payments start at end year
+/ x % */\ 1+y
91.6116
NB. present value, payments start at beginning year
+/ x % */\ 1, }: 1+y
96.6911
NB. future values, payments start at beginning year
r * +/\ x % 1, }: r=. */\ 1+y
21 48.3 82.998 119.778
Rule of 78
y=. 6 NB. amortization period
(% {.) |. +/\i. 1+y NB. declining balances
1 0.714286 0.47619 0.285714 0.142857 0.047619 0
Work Done
Calculation of work done in periods given the capacity. Work exceeding capacity is carried forward to the next period.
capacity=. 50 100 125 150 200 demand=. 5$100 capacity + 2 -/\ >./\ 0, +/\ capacity - demand 50 100 125 125 100
Internal Rate of Return
Internal rate of return for a project that requires initial investment of $90 and brings revenue $30, $40, $20 and $10 over next 4 years, after which terminates can be calculated as
(#~1=*) %1{::p. _90 30 40 20 10
1.05202