HP HP-28S - FIB2 (Fibonacci Numbers, Loop Version)

FIB2 (Fibonacci Numbers, Loop Version)
Arguments Results
1: n
Techniques:
• IF ... THEN ... ELSE ... END. FIB2 uses the program-structure
form of the conditional. (FIB1 uses IFTE.)
• START
... NEXT (definite loop). To calculate F
n
,
FIB2 starts with Fa
and F1 and repeats a loop to calculate successive F/s.
Program
. :~:
. ::::
IF n ,:;
THEt·j n
EU::;E
I) 1
2 n
::H A F.: T
DUP
F.:OT
+
t~E:'<T
::;~'lAP DF.:OP
HlD
I ENTER J
~ FIB2J 8TO J
Comments
Begin the program .
Create a local variable.
Begin
the defining program .
Ifn~l,
Then FIl = n;
Begin ELSE clause.
Put Fa and F1 on the stack.
From 2 to n,
Do the following loop:
Make a copy of the latest F (ini-
tially Fj).
Move the previous F (initially Fa)
to level 1.
Calculate the next F (initially F2)'
Repeat the loop.
Drop FIJ - l'
End ELSE clause.
End the defining program.
End the program.
Put the program on the stack.
Store
the program as FIB2.
248 28: Programming Examples