[
https://issues.apache.org/jira/browse/NUMBERS-150?focusedWorklogId=474430&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-474430
]
ASF GitHub Bot logged work on NUMBERS-150:
------------------------------------------
Author: ASF GitHub Bot
Created on: 25/Aug/20 17:50
Start Date: 25/Aug/20 17:50
Worklog Time Spent: 10m
Work Description: XenoAmess commented on a change in pull request #83:
URL: https://github.com/apache/commons-numbers/pull/83#discussion_r476632088
##########
File path:
commons-numbers-fraction/src/main/java/org/apache/commons/numbers/fraction/Fraction.java
##########
@@ -775,19 +778,45 @@ public Fraction divide(Fraction value) {
*/
@Override
public Fraction pow(final int exponent) {
+ if (exponent == 1) {
+ return this;
+ }
if (exponent == 0) {
return ONE;
}
- if (isZero()) {
- return ZERO;
+ if (exponent == -1) {
+ return this.reciprocal();
}
-
- if (exponent < 0) {
- return new Fraction(ArithmeticUtils.pow(denominator, -exponent),
- ArithmeticUtils.pow(numerator, -exponent));
+ if (this.denominator == 0) {
+ if (exponent > 0) {
+ throw new
ArithmeticException(STRING_THE_DENOMINATOR_MUST_NOT_BE_ZERO);
+ } else {
+ return ZERO;
+ }
+ }
+ if (this.numerator == 0) {
+ if (exponent < 0) {
+ throw new
ArithmeticException(STRING_THE_DENOMINATOR_MUST_NOT_BE_ZERO);
+ } else {
+ return ZERO;
+ }
}
- return new Fraction(ArithmeticUtils.pow(numerator, exponent),
- ArithmeticUtils.pow(denominator, exponent));
+ if (exponent > 0) {
+ return new Fraction(
+ ArithmeticUtils.pow(this.numerator, exponent),
+ ArithmeticUtils.pow(this.denominator, exponent)
+ );
+ }
+ if (exponent == Integer.MIN_VALUE) {
+ return new Fraction(
+ ArithmeticUtils.pow(this.denominator, Integer.MAX_VALUE) *
this.denominator,
Review comment:
@aherbert
No need to use ArithmeticUtils.pow here.
Because:
If this.denominator be 0,1,or -1, then it will never overflow.
Other wise, any other int do pow with Integer.MAX_VALUE will overflow, it
will overflow before we do the multiply.
So here is a tricky but correct implement.
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Issue Time Tracking
-------------------
Worklog Id: (was: 474430)
Time Spent: 0.5h (was: 20m)
> Fraction.pow to correctly handle Integer.MIN_VALUE as the argument
> ------------------------------------------------------------------
>
> Key: NUMBERS-150
> URL: https://issues.apache.org/jira/browse/NUMBERS-150
> Project: Commons Numbers
> Issue Type: Bug
> Components: fraction
> Reporter: Jin Xu
> Priority: Major
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> a bug was discovered by [NUMBERS-149].
> here is the fix pr.
> https://github.com/apache/commons-numbers/pull/83
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