# Fibonacci Numbers - HP -28S Manual

Example. Calculate the ratio of surface to volume for a box 9 inches
high, 18 inches wide, and 21 inches long; make the calculation first in
RPN and then in algebraic syntax.
For the RPN version, first enter the height and width.
~
3:
9 [
ENTER
I
2:
9
.
.
1:
18
18
I
ENTER
I
1IilD1IlIHI _ _ _ _
Then key in the length and execute BOXR.
21
BOXR
The ratio is .428571428571.
Now try the algebraic version.
o
BOXR
[09.18.21 [EVALI
Again, the ratio is .428571428571.
Fibonacci Numbers
3:
2:
1:
.428571428571
1IilD1IlIHI _ _ _ _
3:
2:
.428571428571
1:
.428571428571
1IilD1IlIHI _ _ _ _
Given an integer n, calculate the nth Fibonacci number F
n ,
where
This section includes two programs, each demonstrating an approach
to this problem .
• FIBI is a user function that is defined recursively-its defining ex-
pression contains its own name. FIB! is short, easy to understand,
and can be used with symbolic arguments.
• FIB2 is a user function defined with a program.
It
executes faster
than FIBl, but cannot be used with symbolic arguments.
246
28: Programming Examples