Reference Guide

2-2 RPL Programming Examples
Techniques used in FIB1
 IFTE (if -then-else function). The defining procedure for FIB1 contains the conditional function IFTE, which
can take its argument either from the stack or in algebraic syntax.
 Recursion. The defining procedure for FIB1 is written in terms of FIB1, just as F
n
is defined in terms of F
n-1
and
F
n-2
.
FIB1 program listing
Program: Comments:
«
→ n
'IFTE(n‰1,
n,
FIB1(n-1)+FIB1(n-2))'
Defines local variable n.
The defining procedure, an
algebraic expression. If n ≤ 1,
F
n
= n, else F
n
= F
n-1
+F
n-2
.
»
`O FIB1 K
Stores the program in FIB1.
Checksum: # 14909d (press O %FIB1% !° #MEM# %BYTES% )
Bytes: 113.5
Example: Calculate F
6
. Calculate F
10
using algebraic syntax.
First calculate F
6
.
J
6 %FIB1%
Next, calculate F
10
using algebraic syntax.
O%FIB1% !Ü10 N
FIB2 (Fibonacci Numbers, Loop Version
Level 1
→
Level 1
n
→
F
n
Techniques used in FIB2
 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 F
0
and F
1
and repeats a loop to calculate
successive values of F
i
.