Package org.apfloat.internal

Class IntModMath

java.lang.Object

org.apfloat.internal.IntElementaryModMath

org.apfloat.internal.IntModMath

Direct Known Subclasses:

IntFactor3NTTStepStrategy, IntNTTConvolutionStepStrategy, IntTableFNT, IntWTables

public class IntModMath
extends IntElementaryModMath

Modulo arithmetic functions for int data.

Version:

1.0

Author:

Mikko Tommila

Constructor Summary

Constructors

Constructor	Description
IntModMath()	Default constructor.

Method Summary

Modifier and Type	Method	Description
final int[]	createWTable(int w, int n)	Create a table of powers of n:th root of unity.
int	getForwardNthRoot(int primitiveRoot, long n)	Get forward n:th root of unity.
int	getInverseNthRoot(int primitiveRoot, long n)	Get inverse n:th root of unity.
final int	modDivide(int a, int b)	Modular division.
final int	modInverse(int a)	Modular inverse, that is 1 / a.
final int	modPow(int a, int n)	Modular power.
final int	negate(int a)	Modular negation.

Methods inherited from class org.apfloat.internal.IntElementaryModMath

getModulus, modAdd, modMultiply, modSubtract, setModulus

Methods inherited from class java.lang.Object

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

Constructor Details

IntModMath

public IntModMath()

Default constructor.

Method Details

createWTable

public final int[] createWTable(int w,
 int n)

Create a table of powers of n:th root of unity.

Parameters:

w - The n:th root of unity modulo the current modulus.

n - The table length (= transform length).

Returns:

Table of table[i]=wi mod m, i = 0, ..., n-1.

getForwardNthRoot

public int getForwardNthRoot(int primitiveRoot,
 long n)

Get forward n:th root of unity. This is w.

Assumes that the modulus is prime.

Parameters:

primitiveRoot - Primitive root of the modulus.

n - The transform length.

Returns:

Forward n:th root of unity.

getInverseNthRoot

public int getInverseNthRoot(int primitiveRoot,
 long n)

Get inverse n:th root of unity. This is w-1.

Assumes that the modulus is prime.

Parameters:

primitiveRoot - Primitive root of the modulus.

n - The transform length.

Returns:

Inverse n:th root of unity.

modInverse

public final int modInverse(int a)

Modular inverse, that is 1 / a. Assumes that the modulus is prime.

Parameters:

a - The operand.

Returns:

a-1 mod m.

modDivide

public final int modDivide(int a,
 int b)

Modular division. Assumes that the modulus is prime.

Parameters:

a - The dividend.

b - The divisor.

Returns:

a*b-1 mod m.

negate

public final int negate(int a)

Modular negation.

Parameters:

a - The argument.

Returns:

-a mod m.

modPow

public final int modPow(int a,
 int n)

Modular power. Assumes that the modulus is prime.

Parameters:

a - The base.

n - The exponent.

Returns:

an mod m.