HP HP-28S - Page 244

Program
'2t(htw+htl+wtl)'
I ENTER I
~ BOXS ISTO I
Comments
The defining expression for the
surface area. Evaluating the user
function causes evaluation of this
expression,
returning the area to
the stack.
End the program.
Put the program on the stack.
Store
the program as BOXS.
Example.
One of the advantages of user functions is that they work
in either RPN or algebraic syntax. Calculate the surface of a box 12
inches high, 16 inches wide,
and 24 inches long; make the calculation
first
in RPN and then in algebraic syntax.
For
the RPN version, first enter the height and width.
IUSERI 3:
2: 12
1 2 I ENTER I 1 : 16
16 I ENTER I D!llRI ____ _
Then key in the length and execute BOXS.
~-----------------------,
24 BOXS 3:
2:
1: 1728
D!llRI ____ _
The surface area is 1728 square inches.
Now try the algebraic version.
~ BOXS OJ 12,16,24IEVALI
3:
2: 1728
1: 1728
D!llRI ____ _
Again, the surface area is 1728.
28: Programming Examples 243