**The INPUT Command**

On the HP Prime, the INPUT command can include various types of input forms: numeric fields, choose boxes, and check boxes. You can also restrict which types of input are accepted. This blog entry will cover some of the basic forms of INPUT.

**Basic Form**

INPUT(var, title, label);

var = can be one or a list

title = optional string

label = optional string, number of labels are equal to number of var

The example programs presented (except for IN4) win use one variable.

Here is an example of the basic format. Keep in mind, the title and label strings are optional.

EXPORT IN1( )

BEGIN

// Basic

INPUT(X, "Enter X");

RETURN √(1+X^2);

END;

**Specifying Types**

INPUT( {var, [types allowed]}, title, label);

Type numbers are surrounded in square brackets.

Common Types:

-1 All

0 real numbers

1 integers

2 strings

3 complex numbers

4 matrices

6 lists

8 functions

9 numbers with units

14.? CAS objects

IN2 and IN3 are programs that ask for a specific type. IN2 asks for a matrix (type 4) and IN3 asks for a list (type 6).

EXPORT IN2( )

BEGIN

// Ask for a Matrix

INPUT({{M0,[4]}}, "Matrix");

RETURN M0*TRN(M0);

END;

EXPORT IN3( )

BEGIN

// Ask for a List

INPUT({{L0, [6]}}, "List");

PRINT( );

PRINT("Σx ="+STRING(ΣLIST(L0)));

PRINT("mean = "+STRING(approx(mean(L0))));

PRINT("std dev ="+STRING(approx(steddevp(L0))));

END;

**Checkboxes**

INPUT({{var, n}}, title, label);

n groups the current and next n-1 checkboxes. If you want a checkbox next to each variable, let n = 1. A variable that is checked has a value of 1. Otherwise, the value is 0. Each variable and it's corresponding

*n*are surrounded in curly brackets.

EXPORT IN4( )

BEGIN

// Checkboxes

INPUT( {{A,1}, {B,1}, {C,1}}, "Turn On Variables");

PRINT( );

PRINT("Number of Checks: "+STRING(A+B+C));

END;

If you want to use more than one input form, I advise to keep INPUT types separate.

EXPORT IN5( )

BEGIN

// Checkbox Modes

INPUT( {{M,1}}, "Check for Degrees");

HAngle:=M;

// Input Data

INPUT(A, "Angle");

PRINT( );

PRINT("SIN(2A)² =");

PRINT(SIN(2*A)²);

END;

**Choose Boxes**

This INPUT form will create a choose box (drop down list).

INPUT( {{ var, {choice0, choice1, choice2...} }}, title, label)

Follow this by:

IF var == 0 THEN choice0 instructions...(END;)

ELSE (if there are only two choices) or

IF var ==1 THEN choice1 instructions... END; and so on...

EXPORT IN6( )

BEGIN

INPUT( {{C, {"SI","US"} }}, "Units of g");

IF C==0 THEN

RETURN "g = 9.80665 m/s^2"; KILL;

ELSE

RETURN "g = 32.17404 ft/s^2"; END;

END;

That is some of the ways we can use the INPUT command on the HP Prime. To check out all of the ways INPUT command, including putting the prompts in specific places, check out the help screen for INPUT.

Eddie

This blog is property of Edward Shore. 2014