ch.javasoft.math
Class Prime

java.lang.Object
  ch.javasoft.math.Prime

public class Prime
extends Object

The Prime contains large primes for different integer sizes, and functions around primes see http://primes.utm.edu/lists/2small/0bit.html see http://numbers.computation.free.fr/Constants/Primes/countingPrimes.html

Constructor Summary

Prime()

Method Summary

static int	countPrimes(int till, boolean trace, boolean traceAllPrimes) Counts the primes until (inclusive) till, using default cache size, tracing intermediary counts if trace is true, and printing all primes if traceAllPrimes is true.
static int	countPrimes(int till, int cacheSize, boolean trace, boolean traceAllPrimes) Counts the primes until (inclusive) till, using a cache of size cacheSize, tracing intermediary counts if trace is true, and printing all primes if traceAllPrimes is true.
static int	getPrime(int index) Returns the indexth prime, for instance, 2 if index is 0, 3 if index=1 and so on.
static int	getPrime07(int index) Ten largest 7 bit primes: (2^7 - k), k index of POW_2_TO_07_OFFSETS
static int	getPrime08(int index) Ten largest 8 bit primes: (2^8 - k), k index of POW_2_TO_08_OFFSETS
static int	getPrime15(int index) Ten largest 15 bit primes: (2^15 - k), k index of POW_2_TO_15_OFFSETS
static int	getPrime16(int index) Ten largest 16 bit primes: (2^16 - k), k index of POW_2_TO_16_OFFSETS
static int	getPrime30(int index) Ten largest 30 bit primes: (2^30 - k), k index of POW_2_TO_30_OFFSETS
static int	getPrime31(int index) Ten largest 31 bit primes: (2^31 - k), k index of POW_2_TO_31_OFFSETS
static long	getPrime32(int index) Ten largest 32 bit primes: (2^32 - k), k index of POW_2_TO_32_OFFSETS
static long	getPrime63(int index) Ten largest 63 bit primes: (2^63 - k), k index of POW_2_TO_63_OFFSETS
static int	getPrimeBelow(int n) Returns the largest prime below n.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Prime

public Prime()

Method Detail

getPrime63

public static long getPrime63(int index)

Ten largest 63 bit primes: (2^63 - k), k index of POW_2_TO_63_OFFSETS

Parameters:

index - use 0..length(POW_2_TO_63_OFFSETS)

Returns:

63 bit prime 2^63 - POW_2_TO_63_OFFSETS[index]

getPrime32

public static long getPrime32(int index)

Ten largest 32 bit primes: (2^32 - k), k index of POW_2_TO_32_OFFSETS

Parameters:

index - use 0..length(POW_2_TO_32_OFFSETS)

Returns:

32 bit prime 2^32 - POW_2_TO_32_OFFSETS[index]

getPrime31

public static int getPrime31(int index)

Ten largest 31 bit primes: (2^31 - k), k index of POW_2_TO_31_OFFSETS

Parameters:

index - use 0..length(POW_2_TO_31_OFFSETS)

Returns:

31 bit prime 2^31 - POW_2_TO_31_OFFSETS[index]

getPrime30

public static int getPrime30(int index)

Ten largest 30 bit primes: (2^30 - k), k index of POW_2_TO_30_OFFSETS

Parameters:

index - use 0..length(POW_2_TO_30_OFFSETS)

Returns:

30 bit prime 2^30 - POW_2_TO_30_OFFSETS[index]

getPrime16

public static int getPrime16(int index)

Ten largest 16 bit primes: (2^16 - k), k index of POW_2_TO_16_OFFSETS

Parameters:

index - use 0..length(POW_2_TO_16_OFFSETS)

Returns:

16 bit prime 2^16 - POW_2_TO_16_OFFSETS[index]

getPrime15

public static int getPrime15(int index)

Ten largest 15 bit primes: (2^15 - k), k index of POW_2_TO_15_OFFSETS

Parameters:

index - use 0..length(POW_2_TO_15_OFFSETS)

Returns:

32 bit prime 2^15 - POW_2_TO_15_OFFSETS[index]

getPrime08

public static int getPrime08(int index)

Ten largest 8 bit primes: (2^8 - k), k index of POW_2_TO_08_OFFSETS

Parameters:

index - use 0..length(POW_2_TO_08_OFFSETS)

Returns:

8 bit prime 2^8 - POW_2_TO_08_OFFSETS[index]

getPrime07

public static int getPrime07(int index)

Ten largest 7 bit primes: (2^7 - k), k index of POW_2_TO_07_OFFSETS

Parameters:

index - use 0..length(POW_2_TO_07_OFFSETS)

Returns:

7 bit prime 2^7 - POW_2_TO_07_OFFSETS[index]

getPrime

public static int getPrime(int index)

Returns the index^th prime, for instance, 2 if index is 0, 3 if index=1 and so on. The underlying algorithm is approximately linear in index.

Parameters:

index - the index of the desired prime, 0 for prime 2, 1 for prime 3 and so on

Returns:

the index^th prime

getPrimeBelow

public static int getPrimeBelow(int n)

Returns the largest prime below n. The underlying algorithm is approximately linear in n.

countPrimes

public static int countPrimes(int till,
                              boolean trace,
                              boolean traceAllPrimes)

Counts the primes until (inclusive) till, using default cache size, tracing intermediary counts if trace is true, and printing all primes if traceAllPrimes is true. Returns the number of primes found.

countPrimes

public static int countPrimes(int till,
                              int cacheSize,
                              boolean trace,
                              boolean traceAllPrimes)

Counts the primes until (inclusive) till, using a cache of size cacheSize, tracing intermediary counts if trace is true, and printing all primes if traceAllPrimes is true. Returns the number of primes found.