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Example: loop control with s, Example: loop control with – HP 15c User Manual

Page 112

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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.