Yep, zexy will do the trick.

• zexy - implementation file
• copyleft (c) IOhannes m zmölnig
• 1999:forum::für::umläute:2004
• institute of electronic music and acoustics (iem)

/* get the n-th prime number */ <- what you need, right?

I guess IOhannes m zmölnig could help you more than me on that matter :)

Best regards, Pedro p.s.: sorry for the triple-posted message... I'm slow today.

On Sat, Sep 11, 2010 at 10:50 PM, Pedro Lopes pedro.lopes@ist.utl.ptwrote:

pedro@arkana:~/Apps/pure-data/externals$ find . -name "*prime*" -type f -print 2>/dev/null ./zexy/tests/help-msg/prime.pd ./zexy/tests/help-msg/.svn/text-base/prime.pd.svn-base ./zexy/src/prime.c ./zexy/src/.svn/text-base/prime.c.svn-base ./zexy/reference/prime-help.pd ./zexy/reference/.svn/text-base/prime-help.pd.svn-base ./zexy/reference/.svn/prop-base/prime-help.pd.svn-base

Seems that there are some prime related stuff (not sure what they do.. have to look further into them) in pd-externals, maybe one can do the trick.

On Sat, Sep 11, 2010 at 10:48 PM, Pedro Lopes pedro.lopes@ist.utl.ptwrote:

...

I have no clue if it exists in a pd-object, but its easy to compile and external with some generator from the web:

• http://snippets.dzone.com/posts/show/4247 or

http://snipplr.com/view/1219/c-prime-number-generator/ (do you want it to output numbers on bang? all at the same time - I tested that code just now... seems fine and can be tuned to how many primes you want.)

other way to go: you could grab them from a file (of stored primes) or from an online prime generator =P

On Sat, Sep 11, 2010 at 9:33 PM, Kim Cascone kim@anechoicmedia.comwrote:

...

is there a Pd object for generating prime numbers?

currently I'm:

[1 2 3 5 7 9...97] | | [metro] | | | [list=dripslow] | [foo]

---

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-- Pedro Lopes (ongoing MSc) contact: pedro.lopes@ist.utl.pt website: http://web.ist.utl.pt/Pedro.Lopes

-- Pedro Lopes (ongoing MSc) contact: pedro.lopes@ist.utl.pt website: http://web.ist.utl.pt/Pedro.Lopes

On Sun, 12 Sep 2010, Frank Barknecht wrote:

On Sat, Sep 11, 2010 at 10:48:05PM +0100, Pedro Lopes wrote:

...

other way to go: you could grab them from a file (of stored primes) or from an online prime generator =P

Actually that's what I would do. And did, see attachment. The numbers come from http://primes.utm.edu/lists/small/1000.txt They are included twice to allow random and sequential access to the first 1000 primes.

Also, because the 1000th prime is 7919 and because 7919*7919 = 62710561 >= 16777216, then that list of primes is enough for anything you can do with pd's normal floats. It can even be said that you only would ever need the first 574 primes when using the float format to represent whole numbers : the 574th prime is the biggest prime you'll need to figure out that any bigger float is a prime number, up to the limit where whole odd floats stop to exist. It's because it's the last prime before 4096, and 4096*4096 = the limit itself.

| Mathieu Bouchard ------------------------------ Villeray, Montréal, QC

Mathieu Bouchard wrote:

On Sat, 11 Sep 2010, Kim Cascone wrote:

...

is there a Pd object for generating prime numbers? currently I'm: [1 2 3 5 7 9...97]

1 is not a prime number. (9 is not a prime number either)

whaat? we live under new rules?

i'm astonished one guy speaking can thinks he makes some 'truth'

hey

sevy

On Sun, 12 Sep 2010, ydegoyon@gmail.com wrote:

i just read '1 is not a prime number' of course 9 is not, ut a prime number can only be divided by 1 and itself, so why 1 can't be?

http://fr.wikipedia.org/wiki/Nombre_premier

we all know that

who is that 'we' ? strange...

| Mathieu Bouchard ------------------------------ Villeray, Montréal, QC

On Sun, 12 Sep 2010, Claude Heiland-Allen wrote:

A prime number has exactly two factors (1 and itself). I attached an abstraction to generate a list of all factors of a number, which could be used to see if a number is prime (inefficiently).

This slightly modified version runs in time O(sqrt(n)) instead of O(n)...

I'm not not counting the step of putting the factors together as list, but if I did, we'd have to write it as O(sqrt(n)+factors^2) and O(n+factors^2) respectively. This could be fixed using the usual messagebox trick.

| Mathieu Bouchard ------------------------------ Villeray, Montréal, QC