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https://issues.apache.org/jira/browse/LANG-662?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12968469#action_12968469
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Christian Semrau commented on LANG-662:
---------------------------------------
The current implementation:
{code:title=Fraction.java|borderStyle=solid}
private static int greatestCommonDivisor(int u, int v) {
//if either op. is abs 0 or 1, return 1:
if (Math.abs(u) <= 1 || Math.abs(v) <= 1) {
return 1;
}
{code}
The case u==0 || v==0 is already handled at the calling site (). So you might
switch to testing for abs==1 only:
{code:title=Fraction.java|borderStyle=solid}
private static int greatestCommonDivisor(int u, int v) {
// the case u==0 || v==0 is handled by the caller.
// if either op. is abs 1, return 1:
if (Math.abs(u) == 1 || Math.abs(v) == 1) {
return 1;
}
{code}
Dropping this test altogether does not change correctness, but might influence
performance. If you expect many fractions with numerator 1 or denominator 1,
keep the test.
> org.apache.commons.lang3.math.Fraction does not reduce (Integer.MIN_VALUE,
> 2^k)
> -------------------------------------------------------------------------------
>
> Key: LANG-662
> URL: https://issues.apache.org/jira/browse/LANG-662
> Project: Commons Lang
> Issue Type: Bug
> Components: lang.math.*
> Affects Versions: 3.0
> Reporter: Christian Semrau
> Priority: Minor
>
> The greatestCommonDivisor method in class Fraction does not find the gcd of
> Integer.MIN_VALUE and 2^k, and this case can be triggered by taking
> Integer.MIN_VALUE as the numerator. Note that the case of taking
> Integer.MIN_VALUE as the denominator is handled explicitly in the
> getReducedFraction factory method.
> {code:title=FractionTest.java|borderStyle=solid}
> // additional test cases
> public void testReducedFactory_int_int() {
> // ...
> f = Fraction.getReducedFraction(Integer.MIN_VALUE, 2);
> assertEquals(Integer.MIN_VALUE / 2, f.getNumerator());
> assertEquals(1, f.getDenominator());
> public void testReduce() {
> // ...
> f = Fraction.getFraction(Integer.MIN_VALUE, 2);
> result = f.reduce();
> assertEquals(Integer.MIN_VALUE / 2, result.getNumerator());
> assertEquals(1, result.getDenominator());
> {code}
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