1. Laptop Instrument
Meeting 4
January 29, 2018

2. ChucK Program 1
// Plays random frequencies // Connect unit generator SinOsc s => dac; // Start loop while (true) { // Generate random frequency // and assign to s Std.rand2f(30.0,1000.0) => s.freq; // Play for 100 milliseconds 100::ms => now; }

3. ChucK Program 2
// Plays octaves // Connect unit generator SinOsc s => dac; // Set starting frequency as a real number 30.0 => float playfreq; // Start loop while (playfreq <= 10000) { // Set frequency playfreq => s.freq; // Play for 2 seconds 2::second => now; // Double frequency 2 *=> playfreq; }

4. Low Notes
Double bass: E or C
Tuba: D
Contrabassoon: B flat

5. Low Notes: Pipe Organ Massey Memorial Organ: 5640 pipes
Chautauqua Institution, New York

6. What is a computer program?
A sequence of statements. Either
Statements end with a terminator (for example, ;)
Statements are separated with a separator
Statements are executed in order. But
There may be branches
There may be loops

7. What might go wrong?
A syntax error: when the rules of the language are not followed
A semantic error: perfect syntax, but the wrong result due to
Logic
Typos

8. Variables and values Variable names: identifiers Value types
An identifier is a sequence of characters and digits, starting with a character. Capitalization counts.
Variables are assigned values
Value types
int : integer (signed)
float : real number (signed), a number with a decimal point
time : internal to ChucK, sometimes called ChucKian
dur : duration

9. Storing and Calculating
Before using a variable, it must be declared. This action sets aside a space of the proper shape to hold the value.
Declaring:
int foo;
dur short;
float some;

10. Storing and Calculating (2)
Once declared, a value of the correct type can be assigned (stored) in the space named by the variable.
Assigning: value on left, location on right, =>
2 => foo;
10::ms => short;
Declaring and assigning together:
120.0 => float some;

11. Storing and Calculating (3)
Example
120.0 => float some; //declare and initialize
some
120.0

12. Storing and Calculating (4)
Arithmetic
120.0 => float some;
some => some; // increment
some
220.0

13. Storing and Calculating (5)
Arithmetic
120.0 => float some;
some => some;
=> some; //increment shorthand
some
320.0

14. Storing and Calculating (6)
0 => int i; //declare and initialize

15. Storing and Calculating (7)
0 => int i; i++; // increment by 1 1

16. Peeking
<<< i >>>; <<< “Answer:” , i >>>;

17. Exercise
After each step, use the ChucK “print” statement to display the value of the answer. // Declare foo as an integer and store 3 // Increment foo by 5 // Increment foo by 1 // Multiply foo by 4 // Subtract 11 from foo // Divide foo by 7
Answer is 3. Integer divide.