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From "Benjamin Croizet (JIRA)" <>
Subject [jira] Created: (MATH-251) Improve the Fraction class to avoid overflow problems and increase features
Date Sat, 28 Mar 2009 08:59:50 GMT
Improve the Fraction class to avoid overflow problems and increase features

                 Key: MATH-251
             Project: Commons Math
          Issue Type: Improvement
    Affects Versions: 1.2
         Environment: java version "1.6.0_12"
Java(TM) SE Runtime Environment (build 1.6.0_12-b04)
Java HotSpot(TM) Client VM (build 11.2-b01, mixed mode, sharing)

Windows XP

Eclipse Ganymede 3.4.1
            Reporter: Benjamin Croizet
            Priority: Minor
             Fix For: 2.0

Hello everybody,

I've improved and extended the _*Fraction*_ class for my personal needs, but it could be nice
to incorporate it within the _commons-math_ library., either by modifying the current _*Fraction*_
class, or by creating a new class which could be called _*AdvancedFraction*_ or something
like that. I've tried to keep all features from the original _*Fraction*_ class.

{color:green}New features :{color}
* I needed to avoid overflow problem. As a result, I've changed numerator and denominator
to _*BigInteger*_ and all associated methods / constructors.
* I've also added other methods and static fields such as :
public String toString()
public Fraction add(int i)
public Fraction subtract(int i)
public Fraction multiply(int i)
public Fraction divide(int i)
public Fraction pow(int exponent)
public double pow(Fraction exponent)
public BigDecimal bigDecimalValue()
public Fraction clone()
public double percentageValue()
public static Fraction ONE_HALF = new Fraction(1, 2)
public static Fraction ONE_QUARTER = new Fraction(1, 4){code}
* I've made sure that the original Junit test within the _*FractionTest*_ class are all right
(I've just commented the overflow tests)
* I've made sure that checkstyle is all right without any tabs

{color:red}Obviously, some things need to be reworked or improved :{color}
* Some methods are still naively implemented, such as
public Fraction add(Fraction fraction)
public Fraction subtract(Fraction fraction)
{code} because I don't have converted the original _*private Fraction addSub(Fraction fraction,
boolean isAdd)*_ method.
* The original _*private Fraction(double value, double epsilon, int maxDenominator, int maxIterations)*_
constructor may use _*BigDecimal*_ instead of _*double*_. I'm not sure it is relevant.
* Junit tests have to be written with news methods (such as _*pow*_)
* Some minor adaptations have to be done in the _*FractionFormat*_ class (change _*getDenominator()*_
by _*getDenominatorAsInt()*_ for instance)

You'll find my work in the attached zip file :
- The _*Fraction*_ and _*FractionTest*_ classes
- The javadoc generated with public and private fields and methods (to show you a complete

Thank you.

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