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/*
* $Id: ResidueRing.java 3366 2010-10-24 13:02:14Z kredel $
*/
package edu.jas.poly;
import java.util.Random;
import java.util.List;
import java.util.ArrayList;
import java.io.Reader;
import org.apache.log4j.Logger;
import edu.jas.structure.ElemFactory;
import edu.jas.structure.RingElem;
import edu.jas.structure.RingFactory;
/**
* Residue ring factory based on RingElem and RingFactory module.
* Objects of this class are immutable.
* @author Heinz Kredel
*/
public class ResidueRing >
implements RingFactory< Residue > {
private static final Logger logger = Logger.getLogger(ResidueRing.class);
//private boolean debug = logger.isDebugEnabled();
/** Ring element for reduction.
*/
protected final C modul;
/** Ring factory.
*/
protected final RingFactory ring;
/** Indicator if this ring is a field.
*/
protected int isField = -1; // initially unknown
/** The constructor creates a ResidueRing object
* from an ring factory and a modul.
* @param r ring factory.
* @param m modul.
*/
public ResidueRing(RingFactory r, C m) {
ring = r;
if ( m.isZERO() ) {
throw new IllegalArgumentException("modul may not be null");
}
if ( m.isONE() ) {
logger.warn("modul is one");
}
if ( m.signum() < 0 ) {
m = m.negate();
}
modul = m;
}
/**
* Is this structure finite or infinite.
* @return true if this structure is finite, else false.
* @see edu.jas.structure.ElemFactory#isFinite()
*/
public boolean isFinite() {
throw new UnsupportedOperationException("not implemented");
//return ring.isFinite();
}
/** Copy Residue element c.
* @param c
* @return a copy of c.
*/
public Residue copy(Residue c) {
return new Residue( c.ring, c.val );
}
/** Get the zero element.
* @return 0 as Residue.
*/
public Residue getZERO() {
return new Residue( this, ring.getZERO() );
}
/** Get the one element.
* @return 1 as Residue.
*/
public Residue getONE() {
Residue one = new Residue( this, ring.getONE() );
if ( one.isZERO() ) {
logger.warn("one is zero, so all residues are 0");
}
return one;
}
/** Get a list of the generating elements.
* @return list of generators for the algebraic structure.
* @see edu.jas.structure.ElemFactory#generators()
*/
public List> generators() {
List rgens = ring.generators();
List> gens = new ArrayList >( rgens.size() );
for ( C c: rgens ) {
gens.add( new Residue(this,c) );
}
return gens;
}
/**
* Query if this ring is commutative.
* @return true if this ring is commutative, else false.
*/
public boolean isCommutative() {
return ring.isCommutative();
}
/**
* Query if this ring is associative.
* @return true if this ring is associative, else false.
*/
public boolean isAssociative() {
return ring.isAssociative();
}
/**
* Query if this ring is a field.
* @return false.
*/
public boolean isField() {
if ( isField > 0 ) {
return true;
}
if ( isField == 0 ) {
return false;
}
// ideal is prime ?
return false;
}
/**
* Characteristic of this ring.
* @return characteristic of this ring.
*/
public java.math.BigInteger characteristic() {
return ring.characteristic();
}
/** Get a Residue element from a BigInteger value.
* @param a BigInteger.
* @return a Residue.
*/
public Residue fromInteger(java.math.BigInteger a) {
return new Residue( this, ring.fromInteger(a) );
}
/** Get a Residue element from a long value.
* @param a long.
* @return a Residue.
*/
public Residue fromInteger(long a) {
return new Residue( this, ring.fromInteger(a) );
}
/** Get the String representation as RingFactory.
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
return "Residue[ "
+ modul.toString() + " ]";
}
/** Get a scripting compatible string representation.
* @return script compatible representation for this ElemFactory.
* @see edu.jas.structure.ElemFactory#toScript()
*/
//JAVA6only: @Override
public String toScript() {
// Python case
return "ResidueRing(" + modul.toScript() + ")";
}
/** Comparison with any other object.
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
@SuppressWarnings("unchecked") // not jet working
public boolean equals(Object b) {
if ( ! ( b instanceof ResidueRing ) ) {
return false;
}
ResidueRing a = null;
try {
a = (ResidueRing) b;
} catch (ClassCastException e) {
}
if ( a == null ) {
return false;
}
if ( ! ring.equals( a.ring ) ) {
return false;
}
return modul.equals( a.modul );
}
/** Hash code for this residue ring.
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
int h;
h = ring.hashCode();
h = 37 * h + modul.hashCode();
return h;
}
/** Residue random.
* @param n such that 0 ≤ v ≤ (2n-1).
* @return a random residue element.
*/
public Residue random(int n) {
C x = ring.random( n );
// x = x.sum( ring.getONE() );
return new Residue( this, x );
}
/** Residue random.
* @param n such that 0 ≤ v ≤ (2n-1).
* @param rnd is a source for random bits.
* @return a random residue element.
*/
public Residue random(int n, Random rnd) {
C x = ring.random( n, rnd );
// x = x.sum( ring.getONE() );
return new Residue( this, x);
}
/** Parse Residue from String.
* @param s String.
* @return Residue from s.
*/
public Residue parse(String s) {
C x = ring.parse( s );
return new Residue( this, x );
}
/** Parse Residue from Reader.
* @param r Reader.
* @return next Residue from r.
*/
public Residue parse(Reader r) {
C x = ring.parse( r );
return new Residue( this, x );
}
}
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