Michael FicarraAug 19, 2024
Dan Gohman

JavaScript's Math.sqrt will be required to be correctly rounded, and thus deterministic!

https://github.com/tc39/ecma262/pull/3345

In practice, all major implementations are already conforming, but it is nice to have the spec make this guarantee. Thanks to @michaelficarra for championing this change!

Normative: fully define Math.sqrt by michaelficarra · Pull Request #3345 · tc39/ecma262

This matches the behaviour that web engines today already display with the WebAssembly f64.sqrt instruction. /cc @sunfishcode

GitHub
Aug 19, 2024 at 3:36pmWeb
Show threadzwarichAug 19, 2024
@sunfish @michaelficarra Still no NaN canonicalization though, right?
Show threadMichael FicarraAug 19, 2024
@zwarich @sunfish Not exactly NaN canonicalisation, but we do have this: https://tc39.es/ecma262/#sec-numerictorawbytes
ECMAScript® 2025 Language Specification

Introduction This Ecma Standard defines the ECMAScript 2025 Language. It is the sixteenth edition of the ECMAScript Language Specification. Since publication of the first edition in 1997, ECMAScript has grown to be one of the world's most widely used general-purpose programming languages. It is

Show threadDan GohmanAug 19, 2024

@zwarich @michaelficarra JS only has a single NaN value, so Math.sqrt will be fully deterministic, for its part.

Storing NaN into a TypedArray produces nondeterministic bits, but it's not guaranteed to be the bits you got from the computation that produced the NaN.

https://262.ecma-international.org/14.0/#sec-numerictorawbytes

ECMAScript® 2023 Language Specification