As an Electrical Engineering graduation requirement, I had to take "engineering
economy". I took full advantage of my 28S and completed most tests in half the
time it took the others who were using tax tables.
As I need room on my 28S, I'm entering these programs onto the mainframe and I
thought I'd send it on ahead as long as it was typed in.
The following 5 programs are subprograms...
1) FPIN:
<< -> i n '(1+i/100)^n' >>
2) FAIN:
<< -> i n '((1+i/100)^n-1)/(i/100)' >>
3) APIN:
<< -> i n 'i/100*(1+i/100)^n/((1+i/100)^n-1)' >>
4) AGIN:
<< -> i n '((1+i/100)^n-i/100*n-1)/(i/100*(1+i/100)^n-i/100)' >>
5) PGIN:
<< -> i n '((1+i/100)^n-i/100*n-1)/((i/100)^2*(1+i/100)^n)' >>
The following 8 programs can be main programs or subprograms depending on the
user's needs.
Notation: P = present (or initial), F = final, G = gradient, A = payment
F.P means find Final value given present value.
arguments are present value, interest rate per term (e.g., 6)
and number of terms.
1) F.P:
<< -> P i n 'P*FPIN(i,n)' >>
2) P.F:
<< -> F i n 'F/FPIN(i,n)' >>
3) F.A:
<< -> A i n 'A*FAIN(i,n)' >>
4) A.F:
<< -> F i n 'F/FAIN(i,n)' >>
5) A.P:
<< -> P i n 'P*APIN(i,n)' >>
6) P.A:
<< -> A i n 'A/APIN(i,n)' >>
7) A.G:
<< -> G i n 'G*AGIN(i,n)' >>
8) P.G:
<< -> G i n 'G*PGIN(i,n)' >>
Examples: if you have $10,000 now and you want to know what it will
be worth in 5 years at 6% interest per year...
! F
!
0 1 2 3 4 !
+--+--+--+--+--+ ----->time in years
! 5
! P=$10,000
then F = F.P so you would enter: 10000
6
5
F.P
which is $13,382.26
other graphical examples follow...
!
! F
0 1 2 3 n-2 !
F.P & P.F +--+--+--+ ... +--+--+
! n-1 n
!
P !
!
F.A & A.F ! F
0 1 2 3 n-2 n-1!
+--+--+--+ ... +--+--+
! ! ! ! !
A! A! A! A! A!
P.A & A.P !A !A !A !A !A !A
0 ! ! ! ! ! !
+--+--+--+ ... +--+--+
! 1 2 3 n-2 n-1 n
!
P ! (n-1)G !nG
3G ! !
2G ! ! !
A.G G ! ! ! !
0 1 2! 3! 4! n-1! n!
+--+--+--+--+ ... +--+
! ! ! ! ! !
A! A! A! A! A! A!
(n-1)G !nG
P.G 3G ! !
2G ! ! !
G ! ! ! !
0 1 ! ! ! ! !
+--+--+--+--+ ... +--+
!
!
P !