Author: scolebourne
Date: Sat Sep 10 02:55:12 2005
New Revision: 279983
URL: http://svn.apache.org/viewcvs?rev=279983&view=rev
Log:
Document and fix fraction reduction
Modified:
jakarta/commons/proper/lang/trunk/src/java/org/apache/commons/lang/math/Fraction.java
jakarta/commons/proper/lang/trunk/src/test/org/apache/commons/lang/math/FractionTest.java
Modified:
jakarta/commons/proper/lang/trunk/src/java/org/apache/commons/lang/math/Fraction.java
URL:
http://svn.apache.org/viewcvs/jakarta/commons/proper/lang/trunk/src/java/org/apache/commons/lang/math/Fraction.java?rev=279983&r1=279982&r2=279983&view=diff
==============================================================================
---
jakarta/commons/proper/lang/trunk/src/java/org/apache/commons/lang/math/Fraction.java
(original)
+++
jakarta/commons/proper/lang/trunk/src/java/org/apache/commons/lang/math/Fraction.java
Sat Sep 10 02:55:12 2005
@@ -189,9 +189,12 @@
}
/**
- * <p>Creates a <code>Fraction</code> instance with the 2 parts
+ * <p>Creates a reduced <code>Fraction</code> instance with the 2 parts
* of a fraction Y/Z.</p>
*
+ * <p>For example, if the input parameters represent 2/4, then the created
+ * fraction will be 1/2.</p>
+ *
* <p>Any negative signs are resolved to be on the numerator.</p>
*
* @param numerator the numerator, for example the three in 'three
sevenths'
@@ -448,12 +451,18 @@
/**
* <p>Reduce the fraction to the smallest values for the numerator and
- * denominator, returning the result..</p>
+ * denominator, returning the result.</p>
+ *
+ * <p>For example, if this fraction represents 2/4, then the result
+ * will be 1/2.</p>
*
- * @return a new reduce fraction instance, or this if no simplification
possible
+ * @return a new reduced fraction instance, or this if no simplification
possible
*/
public Fraction reduce() {
int gcd = greatestCommonDivisor(Math.abs(numerator), denominator);
+ if (gcd == 1) {
+ return this;
+ }
return Fraction.getFraction(numerator / gcd, denominator / gcd);
}
Modified:
jakarta/commons/proper/lang/trunk/src/test/org/apache/commons/lang/math/FractionTest.java
URL:
http://svn.apache.org/viewcvs/jakarta/commons/proper/lang/trunk/src/test/org/apache/commons/lang/math/FractionTest.java?rev=279983&r1=279982&r2=279983&view=diff
==============================================================================
---
jakarta/commons/proper/lang/trunk/src/test/org/apache/commons/lang/math/FractionTest.java
(original)
+++
jakarta/commons/proper/lang/trunk/src/test/org/apache/commons/lang/math/FractionTest.java
Sat Sep 10 02:55:12 2005
@@ -615,14 +615,31 @@
Fraction f = null;
f = Fraction.getFraction(50, 75);
- f = f.reduce();
- assertEquals(2, f.getNumerator());
- assertEquals(3, f.getDenominator());
+ Fraction result = f.reduce();
+ assertEquals(2, result.getNumerator());
+ assertEquals(3, result.getDenominator());
+
+ f = Fraction.getFraction(-2, -3);
+ result = f.reduce();
+ assertEquals(2, result.getNumerator());
+ assertEquals(3, result.getDenominator());
+
+ f = Fraction.getFraction(2, -3);
+ result = f.reduce();
+ assertEquals(-2, result.getNumerator());
+ assertEquals(3, result.getDenominator());
+
+ f = Fraction.getFraction(-2, 3);
+ result = f.reduce();
+ assertEquals(-2, result.getNumerator());
+ assertEquals(3, result.getDenominator());
+ assertSame(f, result);
f = Fraction.getFraction(2, 3);
- f = f.reduce();
- assertEquals(2, f.getNumerator());
- assertEquals(3, f.getDenominator());
+ result = f.reduce();
+ assertEquals(2, result.getNumerator());
+ assertEquals(3, result.getDenominator());
+ assertSame(f, result);
}
public void testInvert() {
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