hutiefang76 commented on code in PR #336:
URL: https://github.com/apache/commons-math/pull/336#discussion_r4364718991
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commons-math-legacy/src/main/java/org/apache/commons/math4/legacy/ml/distance/CanberraDistance.java:
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@@ -31,9 +31,16 @@ public double compute(double[] a, double[] b) {
MathArrays.checkEqualLength(a, b);
double sum = 0;
for (int i = 0; i < a.length; i++) {
+ final double absA = JdkMath.abs(a[i]);
+ final double absB = JdkMath.abs(b[i]);
final double num = JdkMath.abs(a[i] - b[i]);
- final double denom = JdkMath.abs(a[i]) + JdkMath.abs(b[i]);
- sum += num == 0.0 && denom == 0.0 ? 0.0 : num / denom;
+ final double denom = absA + absB;
+ if (Double.isInfinite(denom) && Double.isFinite(a[i]) &&
Double.isFinite(b[i])) {
+ // Rescale large finite coordinates to avoid intermediate
overflow.
+ sum += JdkMath.abs(a[i] * 0.5 - b[i] * 0.5) / (absA * 0.5 +
absB * 0.5);
+ } else {
+ sum += num == 0.0 && denom == 0.0 ? 0.0 : num / denom;
Review Comment:
Changed to `denom == 0.0 ? 0.0 : num / denom` in `7eaa1d03`. A zero sum of
the absolute values means both coordinates are zero, so the numerator check was
redundant. The 8 Canberra tests pass, including signed zero and subnormal
cases. `mvn clean verify` also passes locally on Java 17/macOS arm64 (3798
tests, 33 skips).
The branch already includes current master `a9aabf60` through merge
`dadaf4cd`, including the `macos-latest` and Zulu/Java 8 runner changes
(`56a8f696` and `a9aabf60`). Both are ancestors of this commit. Hosted CI still
needs to run on the new head.
<sub>AI-generated reply; validation figures are from the local execution
logs.</sub>
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