Plus42: The FOR Function

Plus42:  The FOR Function

About the Plus42 App

Author:  Thomas Okken

App: 

Android:  $9.99

iOS:  $9.99

PC/MacOS/Linux:  Free

Donations Accepted

Link:  https://thomasokken.com/plus42/

Please give Okken some love!   Free42 and Plus42 are both awesome apps and emulators, both emulate the HP 42S engine.  The Plus42 adds the solver of the HP 17B/19B/27S and unit conversions of the HP 48/49/50 family.   The Plus42 can also graph functions.   You can find a lot more information on the link above!

(Disclaimer:  I am not being paid.)

I am now including apps like the Plus42 in my rotation for blogs, please be on the look out for those.  

Today's blog entry will cover one of the additional solver functions for the Plus42:  FOR.

Plus42 FOR Syntax

FOR(INIT:COND:NEXT:EXPR)

INIT:  Initial commands

COND:  condition

If the condition is true:  execute EXPR (there can be more than one EXPR statements), then NEXT

If the condition is false:  the loop ends

NEXT:  next command,  this is where the counter variable is incremented or decremented

EXPR:  the main loop

Examples 

Example 1:  Add from 1 to 4.

HP 39G/Prime Code:

A:=0;

FOR K FROM 1 TO 4 DO  (STEP 1)

A:=A+K;

END;

Plus42 Equation Code:

S=FOR((L(A:0)+L(I:1))×0:G(I)≤4:L(I:G(I)+1):L(A:G(A)+G(I)))

Variables:

S = sum_final answer

A = sum

I = counter variable

Result:  S = 10

S=:   set the result to the variable S, S = A

INIT:  (L(A:0)+L(I:1))×0;  set A = 0 and I = 1

COND:  G(I)≤4;  test if I≤4; if true continue, if false exit the loop

NEXT:  L(I:G(I)+1); this happens at the end of the loop, this is like the general STEP incr/decr command

EXPR: L(A:G(A)+G(I))

The use of the Get function allows the variable to used automatically and not be displayed in the CALC menu.  

Something that threw me off is that the order of NEXT and EXPR, which the EXPR (which I think there could be more than one EXPR statements), I am used to NEXT either at the end of the FOR loop or implied (end of indentation in Python, for example).

Example 2:  Product

Calculate Π(n/4, n=1 to m) = 1/4 * 2/4 * 3/4 * ... * m/4

Plus42 Equation Code:

P=FOR((L(A:1)+L(N:1)+M)×0:G(N)≤IP(M):L(N:G(N)+1):L(A:G(A)×(G(N)÷4)))

Variables:

P = product_final answer

N = counter

M = higher limit

P=:   set the result to the variable P, P = A

INIT:  (L(A:1)+L(N:1)+M)×0; set A = 1, N = 1, ask for M

COND: G(N)≤IP(M); if N ≤ IP(M); if true continue, if false exit the loop

NEXT:  L(N:G(N)+1)

EXPR: L(A:G(A)×(G(N)÷4))

Results:

3 → M; P → 0.0938

6 → M; P → 0.1758

12 → M; P → 28.5507

Example 3:  Recursive

Given an initial condition u_0, calculate the recursion:

u_n = 2 * u_n-1 - 3

for n terms.

Plus42 Equation Code:

S=FOR((U+N+L(I:1))×0:G(I)≤N:L(I:G(I)+1):L(U:2×G(U)-3))

Variables:

S = final answer

U = recursive variable

N = number of terms

S=:  final answer

INIT:  (U+N+L(I:1))×0

COND: G(I)≤N

NEXT:  L(I:G(I)+1)

EXPR:  L(U:2×G(U)-3)

Results, enter U, N first before calculating for S:

2 → U, 3 → N; S → -5

5 → U, 2 → N; S → 11

Enjoy and hope this helps,

Eddie 

All original content copyright, © 2011-2022.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Calculator Programming: Making FOR, WHILE, and REPEAT Loops with IS>, DS<, GOTO, IF, LBL

Calculator Programming:  Making FOR, WHILE, and 
REPEAT Loops with IS>, DS<, GOTO, IF, LBL

Introduction

Say your programming capabilities on your calculator, BASIC portable computer, or programming app does not have the FOR, WHILE, and REPEAT loop structures.  No worries, there are some workarounds we can use.

Today the programs will be demonstrated with the language of the TI-81 and TI-84 Plus CE, but this blog isn't limited to these two calculators.


Simulating FOR Loops with IS> and DS<

The TI-81 (and every Texas Instruments graphing calculator of that family inclusive to the TI-84 Plus CE) has the commands IS> and DS<.

IS>:  Increment and Skip

Syntax:  IS>(variable, target number)

IS> increases the value stored in a variable by 1 and performs a comparison test.  The next command is excited if the increased value is less than or equal to the target number.

IS>(var, target)
[do this command if var + 1 ≤ target]
[skip to this command if var + 1 > target]

Simulating the FOR Loop:

FOR var = begin TO end*
[commands]
NEXT
[commands after loop is over]


* Syntax varies.  For the TI-84 Plus CE:  For(var,begin, end) : [commands] : End

with:

begin → var
LBL [label]
[commands]
IS>(var, end)
GOTO [label]
[commands after loop is over]

The program PRGM1 demonstrates how to accomplish a FOR loop with IS>.  PRGM1 displays the numbers 1 to 10.  The TI-81 section can be programmed by on the TI-81 and TI-84 Plus CE, which the TI-84+ section is for calculators TI-82 and later.

"TI-81"
1→K
Lbl 1
Disp K
IS>(K,10)
Goto 1
Disp "END"
Wait 2
"TI-84+"
For(K,1,10)
Disp K
End
Disp "END"

DS<   

Decrement and Skip

Syntax:  DS<(variable, target number)

DS< decreases the value stored in a variable by 1 and performs a comparison test.  The next command is excited if the increased value is greater than or equal to the target number.  DS< is the opposite of IS>.

DS<(var, target)
[do this command if var - 1 ≥ target]
[skip to this command if var - 1 < target]

Simulating the FOR Loop:

FOR var = begin TO end STEP -1*
[commands]
NEXT
[commands after loop is over]


* Syntax varies.  For the TI-82 to the TI-84 Plus CE, including TI-80 and TI-73:
For(var,begin, end, -1) [commands] End

with:

begin → var
LBL [label]
[commands]
DS<(var, end)
GOTO [label]
[commands after loop is over]

PRGM2 demonstrates the use of DS< and the associated For loop.


"TI-81"
10→K
Lbl 1
Disp K
DS<(K,1)
Goto 1
Disp "END"
Wait 2
"TI-84+"
For(K,10,1,­1)
Disp K
End
Disp "END"

Simulating WHILE and REPEAT Loops

With the proper use of the IF, LBL, and GOTO we can simulate WHILE and REPEAT loops.

Simulated WHILE Loops

WHILE [condition is true]
[commands]
END

* While is available for TI-82 to the TI-84 Plus CE, including TI-73.

can be simulated by:

LBL [label]
[commands]
IF [while condition] 
GOTO [label]

Simulated REPEAT Loops

REPEAT
[commands]
UNTIL [condition]

* The syntax for the TI-82 to the TI-84 Plus CE, including TI-73 is:
Repeat [condition] : [commands] : End

LBL [label]
[commands]
IF [inverse of the repeat condition] 
GOTO [label]

Example:  If the repeat condition is T>5, then the inverse is T≤5.

PRGM3 is a demonstration program on how all three techniques are used to accomplish this:

Start with 1000.  Take the square root.  Keep going until the calculator gets to 1 (by the precision of the calculator).

"TI-81"
1000→K
Lbl 1
√(K)→K
Disp K
If K≠1
Goto 1
Disp "END"
Wait 2
"84+ WHILE"
1000→K
While K≠1
√(K)→K
Disp K
End
Disp "END WHILE"
Wait 2
"84+ REPEAT"
1000→K
Repeat K=1
√(K)→K
Disp K
End
Disp "END REPEAT"

I hope you find these tips useful and helpful.

Eddie

All original content copyright, © 2011-2019.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.

HP Prime Programming Tutorial is now available

HP Prime Programming Tutorial is now available

The HP Prime Programming tutorial is a set of twelve tutorials designed to get up and running on HP’s PPL programming language.  Knowledge of the programming language will help you take your HP Prime further.  The topics covered are:

1.  Help Key, Local Variables, RETURN command

2.  Message box, IF-THEN-ELSE structure, FOR loop

3.  WHILE loop, REPEAT loop, Detecting key presses

4.  CHOOSE command (providing a pop-up menu), CASE structure

5.  Colors, Switching Apps

6.  Subroutines

7.  Drawing Graphics, Cartesian vs Pixel Coordinates

8.  Drawing Lines, Polygons, Arcs, Circles

9. Numerical Calculus

10. Using App Functions in Programs

11. Drawing and using a soft menu

12. Creating custom apps

Firmware Version 13441

Download the PDF file here:  https://drive.google.com/open?id=184JoIhaaOXoEEyfdrY-nOdCVppQ3L9sU

A little history

If you want to look at my original tutorial series that posted during October through December 2013, the first of the series is here: https://edspi31415.blogspot.com/2013/10/hp-prime-programming-tutorial-1-local.html 

However, the HP Prime’s firmware had a lot of updates since then.  And the PDF file has more topics and is up to date. 

On the date of this entry, this blog is one week away from its 7th Anniversary.  This blog’s “birthday” is April 11.  I want to thank you all for your support and compliments, this is labor of love for. 

Enjoy!

Eddie

All original content copyright, © 2011-2018.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.  Please contact the author if you have questions.

HP Prime Programming Tutorial #2: MSGBOX, IF-THEN-ELSE, PRINT, FOR

Welcome to another programming tutorial for the HP Prime. In this session, we will cover MSGBOX, IF-THEN-ELSE, PRINT, and the FOR loop.

---

MSGBOX

MSGBOX: MSGOX takes a string a makes a pop-up message box. Program execution stops until you press a key to acknowledge the message.
Access: Cmds, 6. I/O, 8. MSGBOX

The program COMLOCK: Imagine that you are in charge of setting the combinations for the good, old-school combination locks. This program gives three digit combinations through the use of MSGBOX.

EXPORT COMLOCK()
BEGIN
LOCAL L0;
L0:=RANDINT(3,0,39);**
MSGBOX("SECRET: "+L0(1)+","+L0(2)+","+L0(3));
END;  
** Thanks to Thomas Lake for pointing out my typo.  Apologies for any inconvenience - Eddie (3/21/2014)

---

Other commands that are featured:

RANDINT(n, a, b) generates a list of n integers between a and b. You can leave n out if you desire a single random integer. Picks may be repeated.

The HP Prime's default list variables are designated L0 through L9.

---

Here is a sample output for COMLOCK:

IF-THEN-ELSE

IF-THEN-ELSE: Program structure:
IF condition THEN
do if the condition is true;
ELSE
do if the condition is false;
END;

Access: Tmplt, 2. Branch, 2. IF THEN ELSE

---

Tip: You can leave out the ELSE part if you only want to test to see if a condition is true. Access the simple IF-THEN structure by pressing Tmplt, 2. Branch, 1. IF THEN.

Access <, ≤, ==, etc. by pressing Shift, 6. Note that the double equals is needed to check equality.

---

PRINT

PRINT: The PRINT command prints a sting, result, or a combination of both onto the Prime's Terminal screen. If PRINT is used, the program will end on the terminal (text output) screen. Press a button to exit.

You can access the terminal screen at any time by pressing the ON button, holding it, and then pressing the Divide ( ÷ ) button.

Access: Cmds, 6. I/O, 9. PRINT

---

Tip: To clear the terminal screen, type PRINT(). This is a good way to clear the terminal screen and I usually use this at the beginning of any program if PRINT is going to be used later on.

---

The program QROOTS (yet one more quadratic solver, sorry for not being original guys and gals), demonstrates the use of IF-THEN-ELSE and PRINT.

Here I set the setting variable HComplex to 1, which allows for complex number results.

EXPORT QROOTS(A,B,C)
BEGIN
LOCAL D;
PRINT();
HComplex:=1;
D:=B^2-4*A*C;
IF D≥0 THEN
PRINT("Roots are real.");
ELSE
PRINT("Roots are complex.");
END;
PRINT((-B+√D)/(2*A));
PRINT((-B-√D)/(2*A));
END;

Examples:

QROOTS(1,5,8) returns:

Roots are complex.
-2.5+1.32287565553*i
-2.5-1.32287565553*i

QROOTS(2,-4,-8) returns:

Roots are real.
3.2360679775
-1.2360679775

---

FOR

This section will explore the basic FOR structure:

FOR variable FROM start TO end DO
commands;
END;

All the commands in the loop will be executed a set number of times. Each time a loop finishes, the variable increases by one. The loop terminates when variable=end.

Access: Tmplt, 3. LOOP, 1. FOR

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The program SUMDIV takes any integer and adds up the sum of its divisors. For example, the divisors of 12 are 1, 12, 2, 3, 4, and 6. The sum is 28.

---

Featured Commands in SUMDIV:

idivis: idivis(integer) returns a sequence of all of the divisors if integer. Access: Toolbox, CAS, 5. Integer, 1. Divisors

Any CAS command used in programming will be preceded by "CAS." Not all CAS commands can be used in HP Prime programming at this time.

DIM: returns the dimensions of a sequence, string, or matrix. DIM must be used instead of SIZE to prevent a Bad Argument error.

For sequences or vectors, DIM returns the length in a list {length}.
For strings, DIM returns length as a number.
For matrices, DIM returns the list {number of rows, number of columns}.

Access: Cmds, 1. Strings, 9. DIM

---

The program:

EXPORT SUMDIV(N)
BEGIN
LOCAL S:=0,K,mdiv,ldiv;
mdiv:=CAS.idivis(N);
ldiv:=DIM(mdiv);
FOR K FROM 1 TO ldiv(1) DO
S:=S+mdiv(K);
END;
RETURN S;
END;  

** Thanks to Thomas Lake for pointing out that the variable "mat", which I had in this program was unnecessary.  - Eddie 3/21/2013

 

Examples:
SUMDIV(12) returns 28.
SUMDIV(24) returns 60.
SUMDIV(85) returns 108.

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This concludes this part of the HP Prime Programming Tutorial.

HAPPY HALLOWEEN!

Eddie


This blog is property of Edward Shore. 2013