Transcript TI-Nspire Programming

Josh Schneider
[email protected]
Who this session is for…
 “I’ve never programmed on anything, ever; but I have this class set of TINspires…”
 These guys might benefit too, but some material will be stuff you
already know…
 “I’ve never programmed on a calculator before, but I’ve done some little
scripts here and there on my computer.”
 “I’ve never programmed on the Nspire before, but I have worked on other
TI products.”
 Who will be really bored…
 “I’ve not only done a ton of TI-Basic programs, I’ve also written a few
Apps!”
Why Programming?
1. Programming is a passion of mine. Logic is fun!
2. The amount of work to do always increases, while the
amount of people to do it almost never does. I feel that
truly effective people find ways to automate repetitive
tasks in their every day life.
3. For some students, Programming is a tangible way to
teach abstract concepts of logic, causality, critical
thinking, and even empathy!
“Progra– what?”
 An Algorithm is a list of instructions to accomplish a
goal.
 Think of an Algorithm as a Recipe
 Ingredients become Variable Declarations
 Steps become Code
 Yield becomes Return
 The digital expression of your Algorithm is a
Program.
Scripts vs Programs – An
Aside
 A Programming Language must be translated from the language
to machine language (a process called Compiling, using a
Compiler) before it can be executed.
 Changes take time, you have to recompile each time you want to
run.
 A Scripting Language is translated from the language to machine
language at runtime (Interpreting) using a piece of software
called an Interpreter.
 Changes can be made and tested “on the fly”.
 Easier to debug.
 TI BASIC is technically a scripting language.
Prgm vs Func
 In the world of the TI-Nspire…
 A Program (Prgm) is an expression of an algorithm.
 Variables can be local or global.
 Does not return a response… just output.
 A Function (Func) is an expression of an algorithm that
returns a response.
 Variables must be local.
 The Function must return a response.
 Most of the commands you use in the TI-Nspire are
Functions.
Some Terminology
 Debugging is the process of stepping through code, finding,
and fixing issues.
 A Block is “container for code”. An example, the Prgm and
EndPrgm statements form a Prgm Block. Everything
between those statements are treated as a program.
 A Conditional statement offers boolean criteria (true or
false) and effects based on the response, essentially a choice
for the program.
 A Loop allow you to repeat steps. A loop allow you to
repeat steps. A loop allow you to repeat steps…
Error Terminology
 A Syntax Error generally means that you used a
function or command incorrectly. For instance:
 Solve(2x=0) would produce a syntax error, since the
Solve() command requires an expression, a comma, and
then a variable.
 A Domain Error generally indicates that a calculation
is out of the range of the calculator’s capabilities.
Logic Errors
 The beauty of code:
It does exactly what you tell it to do.
 The frustration of code:
It does exactly what you tell it to do.
 Logic Errors are errors in which the commands and
functions are used in their proper syntax, but the code
doesn’t produce the expected outcome.
 This is usually because of human errors in planning.
 These types of issues are common. At some point, every good
programmer ends up crawling lines of code looking for an
errant line. It’s a rewarding find.
The Program Editor
 So here’s how to get started programming:
On the software:
1. Insert a calculator page.
2. Click on 9:Functions &
Programs
3. Choose 1:Program Editor
4. Choose 1:New…
On the device:
1. Insert a calculator page.
2. Press Menu
3. Choose 9:Functions &
Programs
4. Choose 1:Program Editor
5. Choose 1:New…
• Once you’re here, start filling in the name of
your program, choosing whether it’s a
program or a function, and setting its library
access.
Library Access?
 LibPriv means that the function or program will be available from
any document, but will not display in the catalog.
 LibPub means that the function or program will be available from
any document, and will display in the catalog.
 None or leaving out LibPriv/LibPub means that the function or
program will only be accessible from the current document. (This
is the default)
 You can write your functions or programs in one document using
LibPriv or LibPub, and then access those programs or functions
from any document!
Program #1 – Hello World
The “Hello World”
program is the most
common example of a
new programming
language. It is the simplest
program that can be
written, as it requires no
input, and simply outputs
the text “Hello World”.
Define hello()=
Prgm
Disp “Hello World!”
EndPrgm
A “Hello World” program
is a good way to learn the
most basic structure of a
programming language.
Program #2 – Random List
Generator
With this program, we’ll
spice things up by adding a
loop and input. Since we
want to return a value
(making the result useful
outside the program itself),
we’ll do this one as a
function.
Define randgen(a)=
Func
Local b,i
For the loop, I chose a
For..EndFor loop since we
know how many times we
want to run through.
For i,1,a,1
b[i]:=RandInt(0,9)
EndFor
Return b
The idea is, we run the
function specifying how
many elements we want,
and the function outputs a
list of that many random
integers between 0-9.
EndFunc
Program #3 – Evens or Odds?
With this program, we go
one step further: we’re
adding conditional
statements to the loop we
already know. This one is
being done as a program,
but this time we’ll specify
an input parameter.
Define evenodd(a)=
Prgm
For i,1,dim(a),1
If mod(a[i],2)=0 Then
Disp a[i],” is even.”
Else
For a conditional, we use
If..Then..Else…Endif. The
device will evalute the stuff
between If and Then, and
if it is true, will execute the
statements after Then. If
the statement is not true,
we go to Else, or exit the
conditional nothing else is
specified.
Disp a[i],” is odd.”
EndIf
EndFor
EndPrgm
Next Steps
 Functions are infinitely useful! You can use your
functions to manipulate data in Lists and Spreadsheets,
on graphs (using the Calculate tool), and in Calculator.
 Programs are growing more useful thanks to the TINspire 2.0 addition of the Request and RequestStr
commands for taking input.
 Always remember to Check Syntax and Save before
testing your creations!
Anticipating the User
 Users will do interesting things you did not intend.
 Try to keep your users in mind when writing a new
program.
 Add conditional statements to check incoming data,
and return useful error messages to the user or limit
your program’s response to the data.
Questions?