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Commit c300f08a authored by Vincent Lefèvre's avatar Vincent Lefèvre
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[www] Note about mpfr_subnormalize and the underflow flag.

* mpfr-4.2.1/index.html: updated the note.
* mpfr-4.2.2/index.html: added the same note.
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......@@ -118,7 +118,7 @@ The new tests may fail on some platforms (such as Microsoft Windows), but the ca
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<p>Note also that <code>mpfr_subnormalize</code> has a poorly chosen behavior concerning the underflow flag in a corner case: this is neither underflow after rounding nor underflow before rounding. The behavior will be corrected in <acronym>MPFR</acronym> 4.3.0.</p>
<p>Note also that there are behavior and documentation issues with <code>mpfr_subnormalize</code> and the underflow flag (but not with the computed value). First, <code>mpfr_subnormalize</code> has a poorly chosen behavior concerning the underflow flag in a corner case: this is neither underflow after rounding nor underflow before rounding. Moreover, due to ambiguous documentation on the exact underflow cases (from <a href="https://gitlab.inria.fr/mpfr/mpfr/-/commit/49086d17298227973015e3c6fa97d95ea533cd43">this commit in 2011</a>), the behavior concerning the underflow flag in these cases should actually be currently regarded as unspecified. This was following the discussion <a href="https://sympa.inria.fr/sympa/arc/mpfr/2009-06/msg00000.html"><cite><code>mpfr_subnormalize</code> and inexact, underflow flags</cite></a> in 2009, and in particular, <a href="https://sympa.inria.fr/sympa/arc/mpfr/2009-06/msg00008.html">this message about the exact cases</a>. The behavior and documentation will be corrected in <acronym>MPFR</acronym> 4.3.0.</p>
<h2 id="changes">Changes from version 4.2.0 to version 4.2.1</h2>
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......@@ -69,6 +69,8 @@
<!-- For BUGS, use the latest version from the branch. Changes in this branch will be noted above. -->
<p>See the <a href="https://gitlab.inria.fr/mpfr/mpfr/-/blob/4.2/BUGS"><samp>BUGS</samp></a> file. The <a href="mpfr.html#Reporting-Bugs"><cite>Reporting Bugs</cite></a> section of the <acronym>MPFR</acronym> manual gives details on how to report new bugs.</p>
<p>Note also that there are behavior and documentation issues with <code>mpfr_subnormalize</code> and the underflow flag (but not with the computed value). First, <code>mpfr_subnormalize</code> has a poorly chosen behavior concerning the underflow flag in a corner case: this is neither underflow after rounding nor underflow before rounding. Moreover, due to ambiguous documentation on the exact underflow cases (from <a href="https://gitlab.inria.fr/mpfr/mpfr/-/commit/49086d17298227973015e3c6fa97d95ea533cd43">this commit in 2011</a>), the behavior concerning the underflow flag in these cases should actually be currently regarded as unspecified. This was following the discussion <a href="https://sympa.inria.fr/sympa/arc/mpfr/2009-06/msg00000.html"><cite><code>mpfr_subnormalize</code> and inexact, underflow flags</cite></a> in 2009, and in particular, <a href="https://sympa.inria.fr/sympa/arc/mpfr/2009-06/msg00008.html">this message about the exact cases</a>. The behavior and documentation will be corrected in <acronym>MPFR</acronym>4.3.0.</p>
<h2 id="changes">Changes from version 4.2.1 to version 4.2.2</h2>
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