RFR: JDK-8316708: Augment WorstCaseTests with more cases [v8]

[Raffaello Giulietti]

On Wed, 28 Feb 2024 06:08:18 GMT, Joe Darcy <darcy at 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.
>
> Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Respond to review feedback, adjust worst-case bounds.

test/jdk/java/lang/Math/WorstCaseTests.java line 35:

> 33: 
> 34: /**
> 35:  * This test containst two distinct kinds of worst-case inputs:

Suggestion:

 * This test contains two distinct kinds of worst-case inputs:

test/jdk/java/lang/Math/WorstCaseTests.java line 39:

> 37:  * 1) Exact numerical results that are nearly half-way between
> 38:  * representable numbers or very close to a representable
> 39:  * number. (Half-way caess are hardest for round to nearest even;

Suggestion:

 * number. (Half-way cases are hardest for round to nearest even;

test/jdk/java/lang/Math/WorstCaseTests.java line 43:

> 41:  * roundings.)
> 42:  *
> 43:  * 2) Worst-case errors as observed emprically across different

Suggestion:

 * 2) Worst-case errors as observed empirically across different

test/jdk/java/lang/Math/WorstCaseTests.java line 46:

> 44:  * implementations that are not correctly rounded.
> 45:  *
> 46:  * For the first categpory, the "Table Maker's Dilemma" results from

Suggestion:

 * For the first category, the "Table Maker's Dilemma" results from

test/jdk/java/lang/Math/WorstCaseTests.java line 48:

> 46:  * For the first categpory, the "Table Maker's Dilemma" results from
> 47:  * Jean-Michel Muller and Vincent Lefèvre, are used.
> 48:  * See http://perso.ens-lyon.fr/jean-michel.muller/TMD.html for original

Suggestion:

 * See https://perso.ens-lyon.fr/jean-michel.muller/TMD.html for original

test/jdk/java/lang/Math/WorstCaseTests.java line 50:

> 48:  * See http://perso.ens-lyon.fr/jean-michel.muller/TMD.html for original
> 49:  * test vectors from 2000 and see
> 50:  * http://perso.ens-lyon.fr/jean-michel.muller/TMDworstcases.pdf with

Suggestion:

 * https://perso.ens-lyon.fr/jean-michel.muller/TMDworstcases.pdf with

test/jdk/java/lang/Math/WorstCaseTests.java line 245:

> 243:             {-0x1.842d8ec8f752fp+21,    -0x1.6ce864edeaffdp-1},
> 244:             {-0x1.07e4c92b5349dp+4,     +0x1.6a096375ffb23p-1},
> 245:             // {-0x1.13a5ccd87c9bbp+1008,  -0x1.27b3964185d8dp-1}, // check -- need +/-

High-precision computations confirm `-0x1.27b3964185d8dp-1`

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/15879#discussion_r1509239002
PR Review Comment: https://git.openjdk.org/jdk/pull/15879#discussion_r1509239088
PR Review Comment: https://git.openjdk.org/jdk/pull/15879#discussion_r1509239189
PR Review Comment: https://git.openjdk.org/jdk/pull/15879#discussion_r1509239253
PR Review Comment: https://git.openjdk.org/jdk/pull/15879#discussion_r1509239477
PR Review Comment: https://git.openjdk.org/jdk/pull/15879#discussion_r1509239558
PR Review Comment: https://git.openjdk.org/jdk/pull/15879#discussion_r1509239711