2 Random

2 Random - Random numbers Random numbers The random()...

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Unformatted text preview: Random numbers Random numbers The random() function has two versions: random(5) returns a decimal value between 0 and up to but not including 5.0 random(-5, 10.2) returns a decimal value between ­5.0 and up to but not including 10.2. To drop the decimal part of a random number, use the int() function. int randNum = int(random(6)); int int( randNum now holds an integer from 0 up to but not including 6: {0,1,2,3,4,5} 1 dice example dice example Let's say I wanted to make an applet that simulated rolling a single six sided die What numbers would be possible? 2 dice example dice example Let's say I wanted to make an applet that simulated rolling a single six sided die What numbers would be possible? {1,2,3,4,5,6} 3 dice example dice example Let's say I wanted to make an applet that simulated rolling a single six sided die What numbers would be possible? {1,2,3,4,5,6} int roll = ?? int ?? 4 dice example dice example Let's say I wanted to make an applet that simulated rolling a single six sided die What numbers would be possible? {1,2,3,4,5,6} int roll = int(random(?,?)); 5 dice example dice example Let's say I wanted to make an applet that simulated rolling a single six sided die What numbers would be possible? {1,2,3,4,5,6} int roll = int(random(?,?)); 6 dice example dice example Let's say I wanted to make an applet that simulated rolling a single six sided die What numbers would be possible? {1,2,3,4,5,6} int roll = int(random(1,7)); 7 A bug with negative arguments A bug with negative arguments What arguments would you use to get this range? {-3,-2,-1,0,1,2,3} int roll = int(random(?,?)); 8 A bug with negative arguments A bug with negative arguments For some reason the low limit is one less. {-3,-2,-1,0,1,2,3} int roll =int(random(-4,4)); 9 Random Walk Random Walk The position or state of an object changes unpredictably (by a random amount) over time Software uses random walks to model many "real life" things including: Weather Stock Prices Load on a web server Chemistry (gas particles) 10 More Random Walk examples More Random Walk examples http://www.mit.edu/~kardar/teaching/projects/ch emotaxis(AndreaSchmidt)/random.htm 11 12 A Random Walk isn't a Random A Random Jump I'd call this a random jump x = int(random(0,400)); 13 A Random Walk isn't a Random A Random Jump I'd call this a random jump x = int(random(0,400)); I'd call this a random walk x = x + int(random(-2,2)); 14 A one­dimensional random walk A The one dimension is the x axis, y doesn't change int x = 150; void setup() { size(300,100); size(300,100); } void draw() { background(0); background(0); ellipse(x,50,40,40); ellipse(x,50,40,40); x = x + int(random(-2,2)); int(random(-2,2)); } 15 Practice Quiz Questions Practice Quiz Questions Fill in the blanks to create the indicated random numbers A random integer from 0 to 10: (including 10) int(random(________)) A random integer from 1 to 100: (including 100) int(random(________)) A random integer from ­5 to 5: (including 5) int(random(________)) 16 ...
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