HP -28S Manual page 63

This is one of the benefits of directories:
If you put general-purpose
programs such as RENAME
in
the HOME directory, you can always exe-
cute them but they don't clutter up the USER menu.
Now you can work in the new directory EE.
Drop the two path lists from the stack.
[ DROP
I [
DROP
I
'""2:-:-------------,
1:
'Rl + INV(lNV(R2)+ INV(
R3»'
------
Store the expression in a variable named EQl
(equation
1). You'll see
the reason for this name later.
c:J
EQ1 [STO
I
IL _____ I
The variable EQl appears in the USER menu.
Let's assume that you'll use this expression for a variety of problems,
each of which you want to treat independently. To do so, you can put
the values for each problem in a subdirectory for that problem.
Create a subdirectory SPl
(series-parallel
1) for the first problem.
CRDIR
[ENTER
I
2:
c:J
SP1 [
ENTER
I
1
3 •
I
~mm
_ _ _ _
The name of the new subdirectory appears in the USER menu. Press
the menu key to switch to SPl.
SPl
I!L.--___ I
The USER menu is empty again because the current directory (SP1) is
empty.
62 4: Repeating Calculations