HP Prime: TrigPlot
App (HP Prime Custom app Tutorial)
Introduction
Here is another example custom app, the TrigPlot, which
plots the following equation:
y = A * sin(Bx + C) + D * cos(Ex + F) + G * sin(Hx + I)^2 +
J * cos(Kx + L)^2
where all angles are in radians. The app uses the global variables A through
L.
Keys
[ Num ]: The user
enters values for A – L. They must be
real (not complex or have a √(-1) component)
[ Plot ]: Enter plot
parameters and choose the color of the plot (purple, blue, green, gold,
red). The plot is against a black
background.
[ View ], Erase A-L:
Sets the variables A through L to 0 (zero).
[ Info ]: Displays
information about the app
Notes
The Info section introduces the user to the app’s concept:
Info()
BEGIN
// This is when the user presses
// Shift+Apps (Info), use Print
// commands
PRINT();
PRINT("TrigPlot App");
PRINT("------------");
PRINT("By Edward Shore");
PRINT("------------");
PRINT("This app plots the
equation");
PRINT("Y = A*SIN(B*X+C) +
D*COS(E*X+F) +");
PRINT("G*SIN(H*X+I)^2 +
J*COS(K*X+L)^2");
PRINT("------------");
PRINT("February 2018");
END;
To ensure the app always runs in Radians mode, I store the
value 1 to AAngle during startup (START).
In addition, I added the Info();
to show the Info screen.
START()
BEGIN
// This happens when the app is
started.
// Set the app to radians angle
mode.
AAngle:=1;
// This is a specific app mode
setting
// unlike HAngle
// Also run the Info screen
Info();
END;
The Plot portion of app is based on the Pixel Plot program
(see http://edspi31415.blogspot.com/2018/02/hp-prime-pixel-plot-how-to-change.html
) where pixels are plotted.
HP Prime Program:
TrigPlot (in app TrigPlot)
#pragma mode( separator(.,;)
integer(h32) )
//Symb()
//BEGIN
// MSGBOX("Symb");
//END;
Plot()
BEGIN
// runs the Plot routine
// set color scheme
LOCAL col1;
col1:={#BF00FFh,#7DF9FFh,
#00FF00h,#D4AF37h,#FF0000h};
// Radians
HAngle:=0;
// localize variables
LOCAL xm,xn,ym,yn;
LOCAL xs,ys,xp,yp;
LOCAL x,y,ch;
// input screen
INPUT({
xm,xn,ym,yn,
{ch,
{"Purple","Blue","Green",
"Gold","Red"}}},
"TrigPlot Setup: Plot",
{"x-min: ","x-max:
",
"y-min: ","y-max:
",
"Color: "});
// set black background
RECT_P(0);
// calulate the scale
xs:=(xn-xm)/320;
ys:=(yn-ym)/−220;
// drawing
// color choice
LOCAL c1:=col1[ch];
// axis information
LOCAL st1,st2;
st1:="x:["+xm+","+xn+"]";
st2:="y:["+ym+","+yn+"]";
TEXTOUT_P(st1,0,0,2,#C0C0C0h);
TEXTOUT_P(st2,0,20,2,#C0C0C0h);
// function
FOR x FROM xm TO xn STEP xs DO
// function
y:=A*SIN(B*x+C)+D*COS(E*x+F)+
G*SIN(H*x+I)^2+J*COS(K*x+L)^2;
// point→pixel, plot
xp:=(x-xm)/xs;
yp:=(y-yn)/ys;
PIXON_P(xp,yp,c1);
END;
// freeze screen
FREEZE;
END;
Num()
BEGIN
// This is where all the variables
are
// entered, in one easy spot. A-L
are
// global in this application.
INPUT({A,B,C,D,E,F,G,H,I,J,K,L},
"TrigPlot Variables");
END;
//SymbSetup()
//BEGIN
// MSGBOX("SymbSetup");
//END;
//PlotSetup()
//BEGIN
// MSGBOX("PlotSetup");
//END;
//NumSetup()
//BEGIN
// MSGBOX("NumSetup");
//END;
Info()
BEGIN
// This is when the user presses
// Shift+Apps (Info), use Print
// commands
PRINT();
PRINT("TrigPlot App");
PRINT("------------");
PRINT("By Edward Shore");
PRINT("------------");
PRINT("This app plots the
equation");
PRINT("Y = A*SIN(B*X+C) +
D*COS(E*X+F) +");
PRINT("G*SIN(H*X+I)^2 +
J*COS(K*X+L)^2");
PRINT("------------");
PRINT("February 2018");
END;
START()
BEGIN
// This happens when the app is
started.
// Set the app to radians angle
mode.
AAngle:=1;
// This is a specific app mode
setting
// unlike HAngle
// Also run the Info screen
Info();
END;
//RESET()
//BEGIN
//MSGBOX("RESET");
//END;
//VIEW "Views", Views()
//BEGIN
// MSGBOX("Views");
//END;
VIEW "Erase A-L",
ERASEAL()
BEGIN
A:=0; B:=0; C:=0; D:=0; E:=0; F:=0;
G:=0; H:=0; I:=0; J:=0; K:=0; L:=0;
END;
Examples
Example 1: y = 2
sin(x + 2) – 3 cos x
A = 2, B = 1, C = 2, D = -3, E =
1 (the rest are zero)
Example 2: y = 2
cos(2x) + 1.5 * cos^2 x
D = 2, E = 2, J = 1.5, K = 1 (the
rest are zero)
Eddie
This blog is property of Edward
Shore, 2018.
