Compute prime numbers : Algorithms « Collections Data Structure « Java

Home
Java
1.2D Graphics GUI
2.3D
3.Advanced Graphics
4.Ant
5.Apache Common
6.Chart
7.Class
8.Collections Data Structure
9.Data Type
10.Database SQL JDBC
11.Design Pattern
12.Development Class
13.EJB3
14.Email
15.Event
16.File Input Output
17.Game
18.Generics
19.GWT
20.Hibernate
21.I18N
22.J2EE
23.J2ME
24.JDK 6
25.JNDI LDAP
26.JPA
27.JSP
28.JSTL
29.Language Basics
30.Network Protocol
31.PDF RTF
32.Reflection
33.Regular Expressions
34.Scripting
35.Security
36.Servlets
37.Spring
38.Swing Components
39.Swing JFC
40.SWT JFace Eclipse
41.Threads
42.Tiny Application
43.Velocity
44.Web Services SOA
45.XML
Java » Collections Data Structure » AlgorithmsScreenshots 
Compute prime numbers
 

/* Compute prime numbers, after Knuth, Vol 1, Sec 1.3.2, Alg. "P".
 * Unlike Knuth, I don't build table formatting into
 * computational programs; output is one per line.
 * <p>
 * Note that there may be more efficient algorithms for finding primes.
 * Consult a good book on numerical algorithms.
 * @author Ian Darwin
 */
public class Primes {
  /** The default stopping point for primes */
  public static final long DEFAULT_STOP = 4294967295L;
  /** The first prime number */
  public static final int FP = 2;

  static int MAX = 10000;

  public static void main(String[] args) {
    long[] prime = new long[MAX];

    long stop = DEFAULT_STOP;
    if (args.length == 1) {
      stop = Long.parseLong(args[0]);
    }

    prime[1= FP;       // P1 (ignore prime[0])
    long n = FP+1;       // odd candidates
    int j = 1;        // numberFound

    boolean isPrime = true;  // for 3

    do {

      if (isPrime) {
        if (j == MAX-1) {
          // Grow array dynamically if needed
          long[] np = new long[MAX * 2];
          System.arraycopy(prime, 0, np, 0, MAX);
          MAX *= 2;
          prime = np;
        }
        prime[++j= n;  // P2
        isPrime = false;
      }
      n += 2;        // P4

      for (int k = 2; k <= j && k < MAX; k++) {  // P5, P6, P8
        long q = n / prime[k];
        long r = n % prime[k];
        if (r == 0) {      
          break;
        }
        if (q <= prime[k]) {    // P7
          isPrime = true;
          break;
        }
      }
      
    while (n < stop);        // P3

    for (int i=1; i<=j; i++)
      System.out.println(prime[i]);
  }
}


           
         
  
Related examples in the same category
1.AnagramsAnagrams
2.Hanoi puzzleHanoi puzzle
3.FibonacciFibonacci
4.Sieve Sieve
5.Find connections using a depth-first searchFind connections using a depth-first search
6.Find connections using hill climbing.
7.Find optimal solution using least-cost
8.Find the lost keysFind the lost keys
9.Compute the area of a triangle using Heron's FormulaCompute the area of a triangle using Heron's Formula
10.Print a table of fahrenheit and celsius temperatures 1
11.Print a table of fahrenheit and celsius temperatures 2
12.Print a table of Fahrenheit and Celsius temperatures 3Print a table of Fahrenheit and Celsius temperatures 3
13.Soundex - the Soundex Algorithm, as described by KnuthSoundex - the Soundex Algorithm, as described by Knuth
14.A programmable Finite State Machine implementation.
15.An extendable Graph datastructure.
16.Utilities for flop (floating-point operation) counting.
17.LU Decomposition
18.Reverse Polish Notation
19.Permutator test
20.implements the LZF lossless data compression algorithm
21.Linear Interpolation
22.Utility class for generating the k-subsets of the numbers 0 to n
23.VersionVersion
java2s.com  | Contact Us | Privacy Policy
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.