HP 15c Manual

 Section 6: Programming Basics 81 
 
Problems 
  1. The  village  of  Sonance  has  installed  a  12-oclock  whistle  in  the 
firehouse  steeple.  The  sound  level  at  the  firehouse  door,  3.2  meters 
from  the  whistle,  is  138  decibels.  Write  a  program  to  find  the  sound 
level at various distances from the whistle. 
 Use the equation L = L0 – 20 log (r/r0), where: L0 is the known sound 
level (138 db) at a point near the source, 
r0 is  the  distance  of  that  point  from  the  source...

 
82 
Section 7 
Program Editing 
There  are  many reasons to  modify a program after  youve  already stored it: 
you might  want  to  add  or  delete  an  instruction  (like O, ©,  or 
¦),  or  you  might  even  find  some  errors!  The  HP-15C  is  equipped  with 
several editing features to make this process as easy as possible. 
The Mechanics 
Making  a  program  modification  of  any  kind  involves  two  steps:  moving  to 
the  proper  line  (the  location  of  the  needed  change)  and  making...

 Section 7: Program Editing 83 
 
The  Back  Step (‚) Instruction. To  move  one  line backwards in 
program  memory,  press ‚ (back  step)  in  Program  or  Run  mode.  This 
function is not programmable. ‚ will scroll (with the key held down) in 
Program mode. Program instructions are not executed. 
Deleting Program Lines 
Deletions  of  program  instructions  are  made  with − (back  arrow)  in 
Program  mode.  Move  to  the  line  you  want  to  delete,  then  press −.  Any 
remaining following lines...

84 Section 7: Program Editing 
 
Lets  start  at  the  end  of  the  program  and  work  backwards.  In  this  way,  deletions 
will not change the line numbers of the preceding lines in the program. 
Keystrokes Display  
| ¥ 000- Program mode. (Assumes position is at line 000.) 
t “ 020 
(or use Â) 020-44,40, 3 Moves position to line 020 
(instruction O + 3.) 
   

 Section 7: Program Editing 85 
 
 
Keystrokes Display  
− 019-      40 Line 020 deleted. 
| ‚ (hold) 016-   45  4 The next line to edit is line 
016 (l 4). 
− 015-      20 Line 016 deleted. 
l 2 016-   45  2 Line 016 changed to l 2. 
t “ 011 
(or hold ‚) 011-44,40, 2 Moves to line 011 (O+ 
2). 
− 010-   42 31 Line 011 deleted. 
| ‚ (hold) 008-      31 Stop! (Single-stepping 
backwards to line 008: ¦.) 
− 007-44,40, 1 ¦ deleted. 
l 1 008-   45  1 Line 008 changed to l 1. 
| ‚ 007-44,40, 1 Back-step to...

86 Section 7: Program Editing 
 
you  can  check  the  program  by executing it  stepwise.  This  is  done  by 
pressing  in Run mode. 
Keystrokes Display  
| ¥  Run mode. 
´ CLEAR Q  Clear storage registers. 
t A  Move to first line of program 
A. 
8 O 1 8.0000 Store a can height. 
2.5 2.5 Enter a can radius. 
 (hold) 00142,21,11 Keycode for line 001 (label). 
     (release) 2.5000 Result of executing line 001. 
 002   44  0 t 0. 
 2.5000 Result. 
 003   43 11 | x. 
 6.2500 Result. 
 004   43...

 Section 7: Program Editing 87 
 
Insertions and Deletions 
After  an  insertion,  the  display  will  show  the  instruction  you  just  added. 
After  a  deletion,  the  display  will  show  the  line  prior  to  the  deleted  (now 
nonexistent) one. 
If  all  space  available  in  memory  is  occupied,  the  calculator  will  not  accept 
any program instruction insertions and Error 4 will be displayed. 
Initializing Calculator Status 
The  contents  of  storage  registers  and  the  status  of...

88 Section 7: Program Editing 
 
 
Keystrokes Display 
´ b . 1 001-42,21,.1 
´ •O 002-42, 7, 2 
1 003-       1   
. 004-      48  
0 005-       0 Interest. 
7 006-       7  
5 007-       5  
® 008-      34  
y 009-      14 (1 + i)n 
* 010-      20 PV (1 + i)n 
| n 011-   43 32  
 
 Load  the  program  and  find  the  future  value  of  $1,000  invested  for  5 
years; of $2,300 invested for 4 years. Remember to use G to run 
a program with a digit label. (Answers: $1,435.63; $3,071.58.) 
 Alter the...

 Section 7: Program Editing 89 
 
Make any necessary modifications in the program to also find and display s, 
the length of the circular arc cut by θ (in radians), according to the equation 
s = r θ. 
Complete the following table: 
θ r ℓ=s 
45° 50 ? ? 
90° 100 ? ? 
270° 100 ? ? 
(Answers:  38.2683 and 39.2699;  141.4214  and  157.0796;  141.4214  and 
471.2389.  
A possible new sequence is: 
´bA |D ´•4 O0  2* ® O1 2÷ 
[ * ´© ´© l0 l1 ´r * 
|n). 
  

 
90 
Section 8 
Program Branching 
and Controls 
Although  the  instructions  in  a  program  are  normally  executed  sequentially, 
it is often desirable to transfer execution to a part of the program other than 
the next line. Branching in the HP-15C may be simple, or it may depend on 
a certain condition. By branching to a previous line, it is possible to execute 
part of a program more than once – a process called looping. 
The Mechanics 
Branching 
The  Go  To (t) Instruction. Simple  branching –...