## Saturday, February 10, 2018

### HP Prime Custom App: GeomCalc

HP Prime Custom App: GeomCalc

Introduction

The app GeomCalc is an example of a custom HP App for the HP Prime.  For general information, please visit this blog entry:  http://edspi31415.blogspot.com/2018/02/hp-prime-intro-to-blank-custom-apps.html

START - The Initial Conditions

Here I set the app’s angle to degrees mode.  Note that I use the variable AAngle instead of the global variable HAngle.  The values for AAngle are slightly different than HAngle:

0:  use the angle setting from Home Settings
2:  Degrees

I want the app to operate with angles in degrees, so I set AAngle to 1.

The last command is a message box containing the word Ready, to let the user know that the app is all set to go.

START()
BEGIN
// Set app angle to degrees
AAngle:=2;
END;

Info – Title and Introduction

I want to leave some basic information about this app.  I recommend that you use the PRINT command rather than the TEXTOUT/WAIT/FREEZE.  Alternatively, you can store a string in ANote.

I prefer using PRINT because I can print multiple lines with appropriate line breaks.

Info()
BEGIN
PRINT();
PRINT("GeomCalc");
PRINT("---------");
PRINT("EWS 2018-02-07");
PRINT("---------");
PRINT("Geometry areas and volumes");
END;

The Symb section – selecting the calculation

In this section, I set the variable I to a choice of one of ten options.  The variable I is a global variable, so I can use determine calculations.  The INPUT command uses a dropdown box.  The general format for a single dropdown box is:

INPUT( { { var, {“choice 1”, “choice 2”, … }}}, … (other parameters)  )

The message box at the end let’s the user know that the choice has been set, and can now proceed to the calculation by pressing [Num].

Symb()
BEGIN
// Choose the calculation
// Global vars are used
INPUT({{I,{"Area: Circle",
"Area: Ellipse",
"Area: Trapezoid",
"Area: Circular Sector",
"Area: Regular Polygon",
"Volume: Sphere",
"Volume: Cylinder",
"Volume: Cone",
"Volume: Box",
"Volume: Ellipsoid"}}},
MSGBOX("It's set!");
END;

The Num section – doing the calculation

When the [Num] is pressed, the user as asked to enter the arguments.  The final result is displayed on the terminal.  Since global variables (including A-Z) is used, values are permanently stored until changed.  In this app, I store the area in the variable E and the volume in V.

There is no default selection, so I use ten IF-THEN structures than a CASE structure.

Num()
BEGIN

IF I==1 THEN
E:=π*R^2;
PRINT();
PRINT("Area: "+E);
END;

IF I==2 THEN
INPUT({A,B},"Area: Ellipse",
{"A: ","B: "});
E:=π*A*B;
PRINT();
PRINT("Area: "+E);
END;

IF I==3 THEN
INPUT({A,B,H},"Area: Trapezoid",
{"A: ","B: ","H: "});
E:=0.5*H*(A+B);
PRINT();
PRINT("Area: "+E);
END;

IF I==4 THEN
INPUT({θ,R},"Area: Circular
Sector",{"Angle (°): ",
E:=θ*π*R^2/360;
PRINT();
PRINT("Area: "+E);
END;

IF I==5 THEN
INPUT({N,S},"Area: Regular
Polygon",{"# sides: ",
"Length: "});
E:=N*S^2/(4*TAN(180/N));
PRINT();
PRINT("Area: "+E);
END;

IF I==6 THEN
V:=4/3*π*R^3;
PRINT();
PRINT("Volume: "+V);
END;

IF I==7 THEN
INPUT({R,H},"Volume: Cylinder",
V:=π*R^2*H;
PRINT();
PRINT("Volume: "+V);
END;

IF I==8 THEN
INPUT({R,H},"Volume: Cone",
V:=π*R^2*H/3;
PRINT();
PRINT("Volume: "+V);
END;

IF I==9 THEN
INPUT({A,B,C},"Volume: Box",
{"A: ","B: ","C: "});
V:=A*B*C;
PRINT();
PRINT("Volume: "+V);
END;

IF I==10 THEN
INPUT({A,B,C},"Volume: Ellipsoid",
{"A: ","B: ","C: "});
V:=4/3*π*A*B*C;
PRINT();
PRINT("Volume: "+V);
END;

END;

Putting It All Together

#pragma mode( separator(.,;) integer(h32) )

Symb()
BEGIN
// Choose the calculation
// Global vars are used
INPUT({{I,{"Area: Circle",
"Area: Ellipse",
"Area: Trapezoid",
"Area: Circular Sector",
"Area: Regular Polygon",
"Volume: Sphere",
"Volume: Cylinder",
"Volume: Cone",
"Volume: Box",
"Volume: Ellipsoid"}}},
MSGBOX("It's set!");
END;

//Plot()
//BEGIN
// MSGBOX("Plot");
//END;

Num()
BEGIN

IF I==1 THEN
E:=π*R^2;
PRINT();
PRINT("Area: "+E);
END;

IF I==2 THEN
INPUT({A,B},"Area: Ellipse",
{"A: ","B: "});
E:=π*A*B;
PRINT();
PRINT("Area: "+E);
END;

IF I==3 THEN
INPUT({A,B,H},"Area: Trapezoid",
{"A: ","B: ","H: "});
E:=0.5*H*(A+B);
PRINT();
PRINT("Area: "+E);
END;

IF I==4 THEN
INPUT({θ,R},"Area: Circular
Sector",{"Angle (°): ",
E:=θ*π*R^2/360;
PRINT();
PRINT("Area: "+E);
END;

IF I==5 THEN
INPUT({N,S},"Area: Regular
Polygon",{"# sides: ",
"Length: "});
E:=N*S^2/(4*TAN(180/N));
PRINT();
PRINT("Area: "+E);
END;

IF I==6 THEN
V:=4/3*π*R^3;
PRINT();
PRINT("Volume: "+V);
END;

IF I==7 THEN
INPUT({R,H},"Volume: Cylinder",
V:=π*R^2*H;
PRINT();
PRINT("Volume: "+V);
END;

IF I==8 THEN
INPUT({R,H},"Volume: Cone",
V:=π*R^2*H/3;
PRINT();
PRINT("Volume: "+V);
END;

IF I==9 THEN
INPUT({A,B,C},"Volume: Box",
{"A: ","B: ","C: "});
V:=A*B*C;
PRINT();
PRINT("Volume: "+V);
END;

IF I==10 THEN
INPUT({A,B,C},"Volume: Ellipsoid",
{"A: ","B: ","C: "});
V:=4/3*π*A*B*C;
PRINT();
PRINT("Volume: "+V);
END;

END;

//SymbSetup()
//BEGIN
// MSGBOX("SymbSetup");
//END;

//PlotSetup()
//BEGIN
// MSGBOX("PlotSetup");
//END;

//NumSetup()
//BEGIN
// MSGBOX("NumSetup");
//END;

Info()
BEGIN
PRINT();
PRINT("GeomCalc");
PRINT("---------");
PRINT("EWS 2018-02-07");
PRINT("---------");
PRINT("Geometry areas and volumes");
END;

START()
BEGIN
// Set app angle to degrees
AAngle:=2;
END;

//RESET()
//BEGIN
// MSGBOX("RESET");
//END;

//VIEW "Views", Views()
//BEGIN
// MSGBOX("Views");
//END;

Examples

Example 1:  Area of a Polygon

Example 2:  Volume of a Cone

I plan to post another example by next week, that one will involve plotting.

Eddie

This blog is property of Edward Shore, 2018

#### 1 comment:

1. nice one, thanks for sharing this

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