Saturday, November 14, 2020

HP Prime: The Percent Function

 HP Prime:  The Percent Function


The Percent Function



The HP Prime has three percent functions.   They are not easily found (through the catalog or in program edit mode, Cmds-More menu).  The functions are:


%

%CHANGE

%TOTAL


% Function


%(x, y)  returns x * y /100.  This returns either x% of y or y% of x.  Due to the communicative multiplication property, you can use the arguments in either order.  


%CHANGE


This the percent change function where the arguments are %CHANGE(old, new).  Formula:  %CHANGE(x, y) = (y - x) / x * 100%


%TOTAL


This calculates the % total given a part and a whole.  Syntax:  %TOTAL(whole, part).  Formula:  %TOTAL(x, y) = y / x * 100%


The program POPTOWN uses the percent functions.  It is a simple game where you invite a certain population to live in a town, and the birth (growth) and death rates are determined by random.


HP Prime Prime Program:  POPTOWN


RESULTS(y,n,g,d,p)

BEGIN

// subroutine

PRINT();

PRINT("Year: "+STRING(y));

PRINT("Population: "+STRING(n));

IF y>0 THEN

PRINT("Growth: "+STRING(g)+"%");

PRINT("Death: "+STRING(d)+"%");

PRINT("Δ%: "+%CHANGE(p,n));

END;

WAIT(0);

END;


// main program

EXPORT POPTOWN()

BEGIN

MSGBOX("You start with 10 

residents, inviting up to 50 

new residents each year.  Can 

growth beat death?");

// 2020-10-24 EWS

// Growth and Death

LOCAL n,y,w,g,d,c,p;

LOCAL v; // number of invites

n:=10;

RESULTS(y,n,g,d,p);

// The game

FOR y FROM 1 TO 5 DO

INPUT({{c,{0,10,20,30,40,50}}},

"Year "+STRING(y),"Invite:");

// all invites move in at the

// beginning of each turn

p:=n;

w:=10*(c-1)+n;

v:=10*(c-1)+v;

g:=RANDINT(5,20);

d:=RANDINT(1,25);

n:=w+IP(%(w,g))-IP(%(w,d));

// empty town scenario

IF n≤0 THEN

MSGBOX("No one survived.");

n:=0; 

END;

RESULTS(y,n,g,d,p);

END;

// End the game results

PRINT("Final Results");

PRINT("Population Change: "+

STRING(n-10));

PRINT("Invited: "+STRING(v));

PRINT("Percent Invite: "+

STRING(ROUND(%TOTAL(n,v),2))

+"%");

END;



Eddie


All original content copyright, © 2011-2020.  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. 


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