/*
 * $Id: Rational.java,v 1.75 2007/02/09 20:07:44 rl Exp $
 *********************************************************
 * kaleido
 *
 *  Kaleidoscopic construction of uniform polyhedra
 *  Copyright © 1991-2007 Dr. Zvi Har’El <rl@math.technion.ac.il>
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *  
 *  3. The end-user documentation included with the redistribution,
 *     if any, must include the following acknowledgment:
 *  	“This product includes software developed by
 *  	 Dr. Zvi Har’El (http://www.math.technion.ac.il/~rl/).”
 *     Alternately, this acknowledgment may appear in the software itself,
 *     if and wherever such third-party acknowledgments normally appear.
 *  
 *  This software is provided ‘as-is’, without any express or implied
 *  warranty.  In no event will the author be held liable for any
 *  damages arising from the use of this software.
 *
 *  Author:
 *	Dr. Zvi Har’El,
 *	Technion, Israel Institue of Technology,
 *	Haifa 32000, Israel.
 *	E-Mail: rl@math.technion.ac.il
 **********************************************************
 */

package kaleido;

/**
 * Class Rational
 * @author  <a href="http://www.math.technion.ac.il/~rl/">Zvi Har’El</a>
 * @version $Id: Rational.java,v 1.75 2007/02/09 20:07:44 rl Exp $
 * @see	    <a href="Rational.java">Class source code</a>
 */
public class Rational {

    int numerator;
    int denominator;
    static final Rational ZERO = new Rational(0, 1);

    /**
     * Private Constructor.
     */
    private Rational(int numerator, int denominator) {
	this.numerator = numerator;
	this.denominator = denominator;
    }

    /**
     * Find the numerator and the denominator using the Euclidean
     * algorithm. The resulting rational is reduced.
     */
    Rational(double x) {
	this(1, 0);
	Rational r = ZERO;
	double s = x;
	for (;;) {
	    if (Math.abs(s) > (double) Integer.MAX_VALUE) return;
	    int f = (int) Math.floor(s);
	    Rational r0 = r;
	    r = new Rational(numerator, denominator);
	    long n = numerator * f + r0.numerator;
	    if (Math.abs(n) > Integer.MAX_VALUE) return;
	    numerator = (int) n;
	    n = denominator * f + r0.denominator;
	    if (Math.abs(n) > Integer.MAX_VALUE) return;
	    denominator = (int) n;
	    if (x == doubleValue()) return;
	    s = 1 / (s - f); 
	}
    }

    double doubleValue() {
	return (double) numerator / denominator;
    }

    Rational compl() {
	return new Rational(numerator, numerator - denominator);
    }

    boolean isCompl(Rational r) {
	return numerator == r.numerator &&
		numerator == denominator + r.denominator;
    }

    boolean isInteger() {
	return denominator == 1;
    }

    boolean isFinite() {
	return denominator != 0;
    }

    boolean isStar() {
	return denominator != 1 && denominator != numerator - 1;
    }

    boolean isValid() {
	return numerator > denominator;
    }

    boolean equals(Rational r) {
	return numerator == r.numerator && denominator == r.denominator;
    }

    boolean equals(int i) {
	return numerator == i && denominator == 1;
    }

    public String toString() {
	if (!isFinite()) return "Infinity";
	if (isInteger()) return "" + numerator;
	return numerator + "/" + denominator;
    }

    boolean equals(double x) {
	return equals(new Rational(x));
    }

    static double compl(double x) {
	return x / (x - 1);
    }

    static int numerator(double x) {
	return new Rational(x).numerator;
    }

    static int denominator(double x) {
	return new Rational(x).denominator;
    }

    static boolean isInteger(double x) {
	return new Rational(x).isInteger();
    }

    static boolean isStar(double x) {
	return new Rational(x).isStar();
    }

    static String toString(double x) {
	return new Rational(x).toString();
    }
}