2011-03-26 7 views
29

Estoy buscando una biblioteca de Java que represente fracciones (números racionales). Por ejemplo, si quiero almacenar la fracción 1/3, no se guardará como 0.33333, que perderá su precisión.¿Hay una biblioteca de números racionales comúnmente utilizada en Java?

Aquí es algunas de las funcionalidades que esperan encontrar en una biblioteca como:

  • getNumerator()
  • getDenominator()
  • add(Rational r1, Rational r2), subtract(Rational r1, Rational r2), multiply(Rational r1, Rational r2), divide(Rational r1, Rational r2)
  • isProper()
  • getCommonDenominator(Collection<Rational> rationals)
  • getSimplified()

que puede poner en práctica una biblioteca tal por mí mismo, aunque me preguntaba si ya existe algo similar.

EDIT: También sería bueno que los implementos de la biblioteca (además de los anteriores) algunos algoritmos numéricos teoría, como getEgyptianFractionsSum() etc.

Respuesta

10

La biblioteca incluye la clase JScienceorg.jscience.mathematics.number.Rational. Además de las fábricas, accesos y operaciones habituales, se pueden construir otras entidades útiles, como Polynomial<Rational>, Vector<Rational> y Matrix<Rational>.

A modo de ejemplo, una función para obtener el mínimo común denominador de una colección de fracciones podría tener este aspecto:

private static LargeInteger lcd(Collection<Rational> fractions) { 
    Rational sum = Rational.ZERO; 
    for (Rational rational : fractions) { 
     sum = sum.plus(rational); 
    } 
    return sum.getDivisor(); 
} 

Los siguientes impresiones declaración 6:

System.out.println(lcd(Arrays.asList(
    Rational.valueOf(1, 2), Rational.valueOf(1, 3)))); 
1

La biblioteca Apfloat tiene muchas características excelentes, rendimiento, precisión, etc. Definitivamente es un mejor BigDecimal que para ser justo funciona pero es bastante simple y ofrece poca funcionalidad.

http://www.apfloat.org/apfloat_java/

Contenido:

el establecimiento de rutas de clases Primer ejemplo La construcción de Apfloats doble y flotan constructor advertencias Apfloats son inmutables precisión salida funciones matemáticas avanzadas enteros Los números complejos números racionales Usando algún otro radix que 10 Igualdad y comparación Formateo

1

Implementé una pequeña clase que se puede utilizar para ese propósito, tal vez también pueda ser útil para usted, use con precaución.

import java.util.ArrayList; 

public class RationalNumber { 

    /** 
    * 
    * @author Suat KARAKUSOGLU 
    * @email [email protected] 
    * This class has 2 kind of constructors 
    * 1. is RationalNumber a=new RationalNumber("3.3"); 
    *  RationalNumber a=new RationalNumber("-3.3"); 
    * With this constructor one can enter the decimal number and also specify whether negative or not 
    * 
    * 2. is RationalNumber a=new RationalNumber(3,5); 
    * With this constructor the first value is nominator and second one is denominator. 
    * 
    * The advantage side of this class is, it prevents the fractional errors while dividing 
    * RationalNumber keeps all denominator and nominator values as it is and when the real value is 
    * needed, the calculation occurs at that time. 
    * 
    * Supports multiply,divide,add,subtract operations on RationalNumber classes. 
    * 
    */ 


    /* 
    * Simple Usage: 
    * 
    * RationalNumber a=new RationalNumber("3.3"); 
    * RationalNumber b=new RationalNumber("4.5"); 
    * System.out.println("a ="+a.getStringValue()); 
    * System.out.println("b ="+b.getStringValue()); 
    * System.out.println("a-b ="+a.subtract(b).getStringValue()); 
    * System.out.println("a ="+a.getStringValue()); 
    * System.out.println("b ="+b.getStringValue()); 
    * RationalNumber k=a.divide(b); 
    * System.out.println("a/b="+k.getStringValue()); 
    * System.out.println("a/b="+k.getDoubleValue()); 
    * 
    * System out results: 
    * 
    * a =33/10 
    * b =9/2 
    * a-b =-6/5 
    * a =33/10 
    * b =9/2 
    * a/b=11/15 
    * a/b=0.7333333333333333 
    * 
    */ 

    public ArrayList<Long> nominators = new ArrayList<Long>(); 
    public ArrayList<Long> denominators = new ArrayList<Long>(); 

    public RationalNumber(String rationalNumberStringValue) { 
     this(parseRationalNumberStringValue(rationalNumberStringValue)[0], 
       parseRationalNumberStringValue(rationalNumberStringValue)[1]); 

    } 

    private static Long[] parseRationalNumberStringValue(
      String rationalNumberStringValue) { 

     boolean positive = true; 
     if (rationalNumberStringValue.charAt(0) == '-') { 
      positive = false; 
      rationalNumberStringValue = rationalNumberStringValue.substring(1); 
     } 

     // 0. index is keeping nominator 
     // 1. index is keeping denominator 
     Long[] nominatorDenominator = new Long[2]; 
     nominatorDenominator[0] = 1l; 
     nominatorDenominator[1] = 1l; 

     String[] splittedNumberArr = rationalNumberStringValue.split("\\."); 
     String denominatorStr = splittedNumberArr[1]; 

     for (int i = 0; i < denominatorStr.length(); i++) { 
      nominatorDenominator[1] *= 10; 
     } 

     rationalNumberStringValue = removeCharAt(rationalNumberStringValue, 
       rationalNumberStringValue.indexOf('.')); 
     nominatorDenominator[0] = Long.valueOf(rationalNumberStringValue); 
     if (!positive) { 
      nominatorDenominator[0] *= -1; 
     } 
     return nominatorDenominator; 

    } 

    public static String removeCharAt(String s, int pos) { 
     return s.substring(0, pos) + s.substring(pos + 1); 
    } 

    public RationalNumber(Integer nominator, Integer denominator) { 

     this((long) nominator, (long) denominator); 

    } 

    public RationalNumber(Long nominator, Long denominator) { 

     nominators.add(nominator); 
     denominators.add(denominator); 
     simplify(); 

    } 

    public RationalNumber(ArrayList<Long> nominatorList, 
      ArrayList<Long> denominatorList) { 

     nominators.addAll(nominatorList); 
     denominators.addAll(denominatorList); 
     simplify(); 

    } 

    public String getStringValue() { 
     return getMultipliedValue(this.nominators) + "/" 
       + getMultipliedValue(this.denominators); 
    } 

    public double getDoubleValue() { 
     return (double) getMultipliedValue(this.nominators) 
       /(double) getMultipliedValue(this.denominators); 
    } 

    public RationalNumber multiply(RationalNumber rationalNumberToMultiply) { 

     RationalNumber mulResult = new RationalNumber(
       rationalNumberToMultiply.nominators, 
       rationalNumberToMultiply.denominators); 
     mulResult.nominators.addAll(this.nominators); 
     mulResult.denominators.addAll(this.denominators); 

     return RationalNumber.simplifyRationalNumber(mulResult); 
    } 

    public RationalNumber divide(RationalNumber rationalNumberToDivide) { 

     RationalNumber divideResult = new RationalNumber(
       rationalNumberToDivide.nominators, 
       rationalNumberToDivide.denominators); 

     // division means multiplication with reverse values 
     ArrayList<Long> tempLongList = divideResult.nominators; 
     divideResult.nominators = divideResult.denominators; 
     divideResult.denominators = tempLongList; 

     return this.multiply(divideResult); 

    } 

    public RationalNumber add(RationalNumber rationalNumberToAdd) { 

     rationalNumberToAdd = RationalNumber 
       .simplifyRationalNumber(rationalNumberToAdd); 

     return new RationalNumber(
       (getMultipliedValue(this.nominators) * getMultipliedValue(rationalNumberToAdd.denominators)) 
         + (getMultipliedValue(this.denominators) * getMultipliedValue(rationalNumberToAdd.nominators)), 
       (getMultipliedValue(this.denominators) * getMultipliedValue(rationalNumberToAdd.denominators))); 

    } 

    public RationalNumber subtract(RationalNumber rationalNumberToSubtract) { 

     rationalNumberToSubtract = RationalNumber 
       .simplifyRationalNumber(rationalNumberToSubtract); 

     RationalNumber subtractTempRational = new RationalNumber(
       rationalNumberToSubtract.nominators, 
       rationalNumberToSubtract.denominators); 

     // Multiply one of its nominators negative value 
     subtractTempRational.nominators.set(0, 
       (subtractTempRational.nominators.get(0) * -1)); 

     // add with its negative value 
     return this.add(subtractTempRational); 

    } 

    private long getMultipliedValue(ArrayList<Long> longList) { 
     Long mulResult = 1l; 
     for (Long tempLong : longList) { 
      mulResult *= tempLong; 
     } 
     return mulResult; 
    } 

    // simplifies original rationalnumber 
    public void simplify() { 
     long tempGcd = 1; 
     long iValue = 1; 
     long jValue = 1; 
     for (int i = 0; i < this.nominators.size(); i++) { 
      iValue = this.nominators.get(i); 
      for (int j = 0; j < this.denominators.size(); j++) { 
       jValue = this.denominators.get(j); 
       tempGcd = gcd(iValue, jValue); 
       this.nominators.set(i, iValue/tempGcd); 
       this.denominators.set(j, jValue/tempGcd); 
      } 
     } 
    } 

    public static RationalNumber simplifyRationalNumber(
      RationalNumber rationalNumberToSimplify) { 
     long tempGcd = 1; 
     long iValue = 1; 
     long jValue = 1; 
     for (int i = 0; i < rationalNumberToSimplify.nominators.size(); i++) { 
      for (int j = 0; j < rationalNumberToSimplify.denominators.size(); j++) { 
       iValue = rationalNumberToSimplify.nominators.get(i); 
       jValue = rationalNumberToSimplify.denominators.get(j); 
       tempGcd = gcd(iValue, jValue); 
       rationalNumberToSimplify.nominators.set(i, iValue/tempGcd); 
       rationalNumberToSimplify.denominators.set(j, jValue/tempGcd); 
      } 
     } 
     return rationalNumberToSimplify; 
    } 

    // Euclidean algorithm to find greatest common divisor 
    public static long gcd(long a, long b) { 

     a = Math.abs(a); 
     b = Math.abs(b); 

     if (a < b) { 
      long temp = a; 
      a = b; 
      b = temp; 
     } 

     if (b == 0) 
      return a; 
     else 
      return gcd(b, a % b); 
    } 

    public RationalNumber add(int integerToAdd) { 

     RationalNumber tempRationalNumber=new RationalNumber(integerToAdd,1); 
     return this.add(tempRationalNumber); 
    } 
    public RationalNumber subtract(int integerToSubtract) { 

     RationalNumber tempRationalNumber=new RationalNumber(integerToSubtract,1); 
     return this.subtract(tempRationalNumber); 
    } 
    public RationalNumber multiply(int integerToMultiply) { 

     RationalNumber tempRationalNumber=new RationalNumber(integerToMultiply,1); 
     return this.multiply(tempRationalNumber); 
    } 
    public RationalNumber divide(int integerToDivide) { 

     RationalNumber tempRationalNumber=new RationalNumber(integerToDivide,1); 
     return this.divide(tempRationalNumber); 
    } 



} 
+0

¿Cómo afecta esto a varios cientos las líneas de clase larga califican como "pequeñas"? ò.O –

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