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https://issues.apache.org/jira/browse/GROOVY-9797?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17300012#comment-17300012
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Paul King commented on GROOVY-9797:
-----------------------------------
See: https://github.com/apache/groovy/pull/1504
> println(-0.0f) does not comply with IEEE754
> -------------------------------------------
>
> Key: GROOVY-9797
> URL: https://issues.apache.org/jira/browse/GROOVY-9797
> Project: Groovy
> Issue Type: Bug
> Components: Groovysh
> Affects Versions: 2.5.7, 2.4.17, 2.5.13, 3.0.6
> Environment: Linux
> Reporter: Jubilee
> Assignee: Paul King
> Priority: Minor
> Labels: double, float
> Fix For: 4.0.0-alpha-3
>
> Original Estimate: 24h
> Time Spent: 2.5h
> Remaining Estimate: 21.5h
>
> IEEE754-2019 (which supersedes all previous floating point standards for
> decimal or binary floating point) states that an implementation *shall* (that
> means "is required to") preserve the sign on floating point numbers when it
> converts numbers to an "external decimal character sequence" (that means
> "prints them the way everyone does, unless you use special formatting
> characters I guess"), singling out the two zeros and the two infinities in
> particular for this treatment.
>
> IEEE754-2019 does not say this for no reason. It's because conformant
> floating point implementations can print the float out and then later read it
> back into its original floating point bit-pattern. A close reading of
> IEEE754-1985 suggests this was always the intention, but this requirement was
> made unambiguously explicit for signed zeros as early as IEEE854-1987.
>
> On all the versions of Apache Groovy's REPL that I was able to trivially
> easily test, println(-0.0f) does not output "-0.0", but outputs "0.0"
> instead. While I am aware that printf is also available in Groovy and can
> allow one to select formatting, this should probably be considered a bug,
> especially given that println in Java (OpenJDK 14) outputs "-0.0" and so do
> Kotlin, Scala, and Clojure with their relevant commands.
>
> This bug suggests there are other errors relevant to IEEE754 compliance in
> relevant formatting and parsing code, so it is a good idea to do a more
> thorough audit as well.
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