On Fri, 22 Sep 2023 05:36:02 GMT, Joe Darcy <da...@openjdk.org> wrote:
> A new paper > > "Accuracy of Mathematical Functions in Single, Double, Double Extended, and > Quadruple Precision" > by Brian Gladman, Vincenzo Innocente and Paul Zimmermann > https://members.loria.fr/PZimmermann/papers/accuracy.pdf > > details the inputs with generate the worst-case observed errors in different > math library implementations. The FDLIBM-related worst cases should be added > to the test suite. test/jdk/java/lang/Math/WorstCaseTests.java line 230: > 228: > 229: // Worst-case observed error > 230: {-0x1.004d1c5a9400bp-1, -0x1.0c6e322e8a28cp-1}, It seems that the exact value y meets `-0x1.0c6e322e8a28cp-1` < y < `-0x1.0c6e322e8a28bp-1`, and is closer to `-0x1.0c6e322e8a28bp-1`. Thus, the correctly rounded result is `-0x1.0c6e322e8a28bp-1`. The truncated (expected) value should be `-0x1.0c6e322e8a28bp-1` as well. test/jdk/java/lang/Math/WorstCaseTests.java line 293: > 291: > 292: // Worst-case observed error > 293: {-0x1.0068b067c6feep-1, +0x1.0c335e2f0727p1}, Similar considerations as for asin above. The "expected" value should be `0x1.0c335e2f0726fp1`. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/15879#discussion_r1334537273 PR Review Comment: https://git.openjdk.org/jdk/pull/15879#discussion_r1334539144
