Useful hints: #1 – Odd/Even numbers (Modulo operator [%] and Bitwise And [&])

Eoin — Thu, 11 Mar 2010 19:21:50 +0000

I’m going to start posting some useful little bits of code up here as i think of them.
This is partly to help with my exceptionally poor memory, and partly to help out anyone who might be interested. I encourage anyone else who knows of some similar little helpful tips to send them to me and i’ll post them up here.

Ok, so here’s a nice simple one to start off. What’s an easy and simple method to determine if a number is odd or even?
The answer lies with the modulo operator (%) or the bitwise AND operator (&).

i%2

Whatever i is, i%2 will evaluate to either 0 or 1.
Or a faster method for determining odd or even numbers would be the Bitwise AND operator (represented by a single ampersand: &):

i&1

So what use is this?

Let’s say you’ve got a for loop:

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for(var i:int = 0; i < 50; i++){
if(i%2){ // Or i&1
//do something for odd numbers
}else{
//do something else for even numbers
}
}

So why would we use the modulo operator if a bitwise AND is faster?
To take this further, you could specify separate code for every nth number:

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for(var i:int = 0; i < 50; i++){
switch(i%4){
case 0:
trace ("run every 4 iterations starting from 0");
break;
case 1:
trace ("run every 4 iterations starting from 1");
break;
case 2:
trace ("run every 4 iterations starting from 2");
break;
case 3:
trace ("run every 4 iterations starting from 3");
break;
}
}

Flock

Eoin — Thu, 28 Jan 2010 02:10:26 +0000

Flock is an interactive media installation created in 2008 by myself (Eoin Griffin), Gerard Mangan and Catherine Philpott. The aim of Flock was to create an interactive environment in a public space that would encourage social interaction between members of the public, particularly strangers that wouldn’t ordinarily interact.

Flock visual prototype

Using camera tracking software, artificial intelligence to simulate the movement of a flock of birds, a webcam, a projector and an artfully created, sturdy frame to house the entire apparatus (thanks Ger!), we were able to successfully complete the tasks we set ourselves for this project.

Credits:

Project Manager: Gerard Mangan

Design & planning: Catherine Philpott, Eoin Griffin, Gerard Mangan

Coding & software implementation: Eoin Griffin (Created using Processing (Java) )

Hardware design & planning: Gerard Mangan

Eoin Griffin » Java

Useful hints: #1 – Odd/Even numbers (Modulo operator [%] and Bitwise And [&])

Flock

Credits: