Primes are useful little critters
Prime numbers sure do come in handy sometimes. Imagine, for example, that you have several timed tasks and you want to make sure that two of them never fire at exactly the same moment. Using primes for the intervals is one surefire way to guarantee that they'll never fire simultaneously (since primes cannot be multiples of each other.)
The Primes are useful little critters article by Aral Balkan, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-Noncommercial 2.0 UK: England License.
This is one of those moments where I realize I shouldn't be blogging but heading to bed...
What other wonderful uses for prime numbers have you found? Do share! 
The Primes are useful little critters article by Aral Balkan, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-Noncommercial 2.0 UK: England License.
Peter
wow that’s cool — finally found a use of primes that is actually useful in my day to day job, thanks Aral
December 19th, 2006 at 1:34 amXiaolei Shi
to generalize your notion, I don’t think the intervals need to be prime only relatively prime, which gives you a lot more choices for intervals. The funny thing is that knowledge (or rather lack thereof) of prime numbers forms the basis of internet security as we know it.
RSA basically consists of two relatively large prime numbers multiplied by each other. It’s secure because it makes the assumption that it is rather difficult to factor large numbers.
Given the vast amount of ’secure’ transactions that occur on the internet, if one were to discover a fast factoring algorithm then this person would be a quantifiable god amongst men. Now what is truly hilarious, dents in this problems have occured (quite recently) in fact from people outside of academia.
December 19th, 2006 at 2:00 amVeryVito
I actually keep a printout of the first few hundred prime numbers next to my monitor , and I refer to it all the time in my daily Flash work (but, dang it, I never thought to write about it on my own site!).
Here’s a trick passed down by the original masters of Disney animation: Even without knowing any math, primes can be an animator’s best friend:
When animating a walking dog, for instance, one can use a looping, 11-frame clip for the movement of the dog’s legs, a 5-frame loop for a wagging tail, 13 frames for eye movements, and a 37-frame sequence for head-bobbing, etc. The result is an overall animation sequence that plays for 26,455 frames (11 * 5 * 13 * 37) before discernably repeating its pattern! Pretty good for a timeline with a total of only 37 actual frames, eh?
December 19th, 2006 at 2:19 amJames O'Reilly
Hey Aral, great minds think alike… check out my blog entry on using primes with animation in Flash. http://www.jamesor.com/2006/09/03/prime-time-animation/
I was considering doing a follow-up entry with using primes with sound. Imagine infinte loops with multiple short tracks at various prime lengths. Never found the time tho.
December 19th, 2006 at 4:06 amMark
HI all
January 15th, 2007 at 7:01 pmIm knew to the idea of finding prime numbers. At the moment i think im going to make a small chip that will calculate all primes up to a certain number in a matter of seconds. The idea is simple , if the number cant be divided by 2 or 3 it is obviously a prime number and is written up onto the list. This could calculate minus prime too im guessing. I want to use this in a science competion held in Ireland each year (The Young Sceintest). But im not sure what it could be used for.If you guys could please write up a list pf all the posibilities it could be used for , your ideas are great so far.
Thanks
Mark
Hi All
January 15th, 2007 at 7:11 pmEach year a science competion is held in Ireland, this is going to be the first year im going to try and enter. I was going to do something about prime numbers. Iv just taught up a simple but efective method of finding them. Take a group of numbers , as big as you want hopefully and can inclued minus numbers , all the numbers that are divisable by 2 or 3 will be taken out of the list so obviously all that is left is the primes . I was hoping to put this into a small microchip and it would display it on a little screen . The only thing is that im not to sure about its uses. I have been looking at your posts and think there great ideas but i think il need a little more. If someone could find some more uses and write them up on a list that would be great.
Thank you
Mark
not sure if i just did a double post or not , sorry if i did
January 15th, 2007 at 7:12 pmaral
Hi Mark,
You can’t find a prime number by eliminating all numbers that are not divisible by 2 and 3. 35, for example, isn’t divisible by 2 or 3 but can be divided by 5 and 7. Prime numbers do not follow an (as of yet known) pattern.
January 15th, 2007 at 11:19 pm