HP HP-15C, Руководство пользователя

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112 Section 10: The Index Register and Loop Control
Keystrokes Display
l % 2.6458
Indirectly recalls contents of R
.2
.
´ X
.2
2.6458
Check: same contents recalled by
directly addressing R
.2
.
Exchanging the X-Register
Keystrokes Display
´ X V
12.3456
Exchanges contents of R
I
and X-
register.
l V
2.6458
Present contents of R
I
.
´ X%
0.0000
Exchanges contents of R
2
(which is
zero) with X.
l % 2.6458
´ X
2
2.6458
Check: directly address R
2
.
Storage Register Arithmetic
Keystrokes Display
10
O + V 10.0000
Adds 10 to R
I
.
l V 12.6458
New contents of R
I
(= old + 10).
| $ O ÷
%
3.1416
Divides contents of R
.2
by

.
l%
0.8422
New contents of R
.2
.
´ X
.2
0.8422
Check: directly address R
.2
.
Example: Loop Control with
e
Remember the program in section 8 which used a loop to calculate
radioactive decay? (Refer to page 93.) This program used a test condition (
x
≥
y ?) to exit the loop when the calculated result passed the given limit (50).
As we've seen in this section, there's another way to control loop execution:
through a stored loop counter that is monitored by the
I
or
e
function.