# [PD] Sieve of erastothen

Pagano, Patrick pat at digitalworlds.ufl.edu
Wed Jan 28 16:48:58 CET 2015

```Hello

I would like to know if there is a way to compute the Sieve of erastothenes with pure data

and spit out numbers which can be used for MIDI notes.

There used to be a simple unix program that i used but it no longer is available.

Has anyone tried this with pd? I found some Java code for it.

pp

/*************************************************************************
*  Compilation:  javac PrimeSieve.java
*  Execution:    java -Xmx1100m PrimeSieve N
*
*  Computes the number of primes less than or equal to N using
*  the Sieve of Eratosthenes.
*
*  % java PrimeSieve 25
*  The number of primes <= 25 is 9
*
*  % java PrimeSieve 100
*  The number of primes <= 100 is 25
*
*  % java -Xmx100m PrimeSieve 100000000
*  The number of primes <= 100000000 is 5761455
*
*  % java PrimeSieve -Xmx1100m 1000000000
*  The number of primes <= 1000000000 is 50847534
*
*
*  The 110MB and 1100MB is the amount of memory you want to allocate
*  to the program. If your computer has less, make this number smaller,
*  but it may prevent you from solving the problem for very large
*  values of N.
*
*
*                  N     Primes <= N
*  ---------------------------------
*                 10               4
*                100              25
*              1,000             168
*             10,000           1,229
*            100,000           9,592
*          1,000,000          78,498
*         10,000,000         664,579
*        100,000,000       5,761,455
*      1,000,000,000      50,847,534
*
*************************************************************************/

public class PrimeSieve {
public static void main(String[] args) {
int N = Integer.parseInt(args);

// initially assume all integers are prime
boolean[] isPrime = new boolean[N + 1];
for (int i = 2; i <= N; i++) {
isPrime[i] = true;
}

// mark non-primes <= N using Sieve of Eratosthenes
for (int i = 2; i*i <= N; i++) {

// if i is prime, then mark multiples of i as nonprime
// suffices to consider mutiples i, i+1, ..., N/i
if (isPrime[i]) {
for (int j = i; i*j <= N; j++) {
isPrime[i*j] = false;
}
}
}

// count primes
int primes = 0;
for (int i = 2; i <= N; i++) {
if (isPrime[i]) primes++;
}
System.out.println("The number of primes <= " + N + " is " + primes);
}
}

Patrick Pagano B.S, M.F.A
Audio and Projection Design Faculty
Digital Worlds Institute
University of Florida, USA
(352)294-2020
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