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 Fn is defined in terms of Fn-1and

Fn-2.

FIB1 program listing

Program:

Comments:

 

 

«

 

→ n

Defines local variable n.

'IFTE(n‰1,

The defining procedure, an

n,

algebraic expression. If n ≤ 1,

FIB1(n-1)+FIB1(n-2))'

Fn = n, else Fn = Fn-1+Fn-2.

»

 

 

 

`OFIB1 K

Stores the program in FIB1.

 

 

 

Checksum: # 14909d (press O%FIB1% !°#MEM# %BYTES%)

Bytes: 113.5

Example: Calculate F6. Calculate F10 using algebraic syntax.

First calculate F6.

J

6%FIB1%

Next, calculate F10 using algebraic syntax.

O%FIB1% !Ü10 N

FIB2 (Fibonacci Numbers, Loop Version

Level 1

→

Level 1

 

 

 

n

→

Fn

 

 

 

Techniques used in FIB2

IF7THEN7ELSE7END. FIB2 uses the program-structure form of the conditional. (FIB1 uses IFTE.)

START7NEXT (definite loop). To calculate Fn, FIB2 starts with F0 and F1 and repeats a loop to calculate successive values of Fi.

2-2 RPL Programming Examples