HP 12C Platinum Instruction Manual page 5

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HP 12C Platinum Using the RPN stack to solve problems efficiently
T
d
Z
c
Y
b
X 3.4567
a
3.4567
L
l
Using the stack registers efficiently does not mean to keep track of all stack register contents all the time. Instead
keeping track of what is happening, like which registers have their contents being used, is helpful.
Practice solving problems with stack registers
Example 5: Now what is the shortest keystroke sequence to find y value if the previous expression is changed for the
one below, given x=3.4567?
Solution: One of the shortest keystroke sequences to compute y in the expression is:
3.4567 gr gF y Þ gF g¿ 2 § + +
In this example, a single shift in the sequence of terms was made. The term 2×ln(x) needs four keystrokes
and does not leave a copy of x in L-register, so it was left as the last term to be computed. The expression
is written like this:
Another sequence to compute the expression is:
3.4567 gr gF \
This sequence uses \ to duplicate the number in the X-register
while a copy of it held in Y-register is retrieved to compute -1/x later
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c c
b b
a a
1.86
(1)
gr gF
3.4567
l
=
y
b b
a a
1.86 1.86
3.46 1.24
(2)
g¿
3.4567 3.4567
= + ×
y x 2 ln( x
1
− + ×
x 2 ln( x )
x
(6)
g¿ 2 § ~
- 5 - HP 12C Platinum Using the RPN stack to solve problems efficiently - Version 1.0
a a
1.86
a
1.24 1.86
2 2.48
(3) (4)
2 §
3.4567 2.00
Figure 8
1
−
)
Figure 9
x
Figure 10
Figure 11
(7)
y - +
(6)
so it can be used to compute 2×ln(x)
(7)
.
a
a
a
4.34
(5)
+
2.48