Ricardo Alves<p>New blog post!</p><p>🧮 Ints Aren’t Integers and Floats Aren’t Real</p><p>Some musings on x86 flags, the CMP instruction, floating point quirks, and why 0.1 + 0.2 might actually break a bridge 🌉</p><p>Also: CTF fun, more TPM stuffssess, and a reminder that breaking stuff on purpose is still the best way to learn 🧨</p><p>Read here: <a href="https://dreaming-of-dragons.blogspot.com/2025/07/ints-arent-integers-and-floats-arent.html" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">dreaming-of-dragons.blogspot.c</span><span class="invisible">om/2025/07/ints-arent-integers-and-floats-arent.html</span></a></p><p><a href="https://mastodon.social/tags/assembly" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>assembly</span></a> <a href="https://mastodon.social/tags/ctf" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>ctf</span></a> <a href="https://mastodon.social/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a> <a href="https://mastodon.social/tags/reversing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>reversing</span></a> <a href="https://mastodon.social/tags/linux" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>linux</span></a> <a href="https://mastodon.social/tags/cybersecurity" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>cybersecurity</span></a> <a href="https://mastodon.social/tags/infosec" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>infosec</span></a></p>
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#floatingpoint
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Janne Moren<p>Approximate floating point exponential in three instructions, with explanation:</p><p><a href="https://specbranch.com/posts/fast-exp/" target="_blank" rel="nofollow noopener" translate="no"><span class="invisible">https://</span><span class="">specbranch.com/posts/fast-exp/</span><span class="invisible"></span></a></p><p>This is the stuff the internet was made for!</p><p><a href="https://fosstodon.org/tags/floatingpoint" class="mention hashtag" rel="tag">#<span>floatingpoint</span></a> <a href="https://fosstodon.org/tags/hpc" class="mention hashtag" rel="tag">#<span>hpc</span></a> <a href="https://fosstodon.org/tags/bithacks" class="mention hashtag" rel="tag">#<span>bithacks</span></a></p>
Matthias Kretz | Vir<p>Why did IEEE specify sqrt(-0) to be -0?! That's … surprising when applied to the interpretation of -0 in the context of complex numbers: <br>sqrt(complex{-0,+0}) is complex{+0,+0}.<br>And also pow(-0, 0.5) is +0. <br>If anything sqrt(-0) should be NaN, but why -0?</p><p><a href="https://floss.social/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a> <a href="https://floss.social/tags/iec60559" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>iec60559</span></a> <a href="https://floss.social/tags/ieee754" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>ieee754</span></a> <a href="https://floss.social/tags/CPlusPlus" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>CPlusPlus</span></a> <a href="https://floss.social/tags/C" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>C</span></a> <a href="https://floss.social/tags/cpp" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>cpp</span></a></p>
N-gated Hacker News<p>🚨 Hold onto your slide rules, nerds! A 2019 post reveals the "magic" of floating point numbers, promising more excitement than a math lecture on a rainy Wednesday. 🧙♂️✨ Spoiler alert: the "tricks" are as thrilling as watching paint dry, but at least you won't sprain anything. 😂<br><a href="http://marc-b-reynolds.github.io/math/2019/02/06/Posit1.html" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">http://</span><span class="ellipsis">marc-b-reynolds.github.io/math</span><span class="invisible">/2019/02/06/Posit1.html</span></a> <a href="https://mastodon.social/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a> <a href="https://mastodon.social/tags/magic" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>magic</span></a> <a href="https://mastodon.social/tags/mathhumor" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mathhumor</span></a> <a href="https://mastodon.social/tags/nerdlife" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>nerdlife</span></a> <a href="https://mastodon.social/tags/techfun" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>techfun</span></a> <a href="https://mastodon.social/tags/codingantics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>codingantics</span></a> <a href="https://mastodon.social/tags/HackerNews" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>HackerNews</span></a> <a href="https://mastodon.social/tags/ngated" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>ngated</span></a></p>
Hacker News<p>Posit floating point numbers: thin triangles and other tricks (2019)</p><p><a href="http://marc-b-reynolds.github.io/math/2019/02/06/Posit1.html" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">http://</span><span class="ellipsis">marc-b-reynolds.github.io/math</span><span class="invisible">/2019/02/06/Posit1.html</span></a></p><p><a href="https://mastodon.social/tags/HackerNews" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>HackerNews</span></a> <a href="https://mastodon.social/tags/PositNumbers" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>PositNumbers</span></a> <a href="https://mastodon.social/tags/FloatingPoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FloatingPoint</span></a> <a href="https://mastodon.social/tags/Mathematics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Mathematics</span></a> <a href="https://mastodon.social/tags/Triangles" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Triangles</span></a> <a href="https://mastodon.social/tags/TechTricks" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>TechTricks</span></a> <a href="https://mastodon.social/tags/HackerNews" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>HackerNews</span></a></p>
FCLC<p>and for the <a href="https://mast.hpc.social/tags/IEEE754" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>IEEE754</span></a> / <a href="https://mast.hpc.social/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a> nerds (you know who you are!) here's a much more definitive answer/breakdown of our IEEE Binary FP32 conformance for the Vector Unit! <a href="https://github.com/tenstorrent/tt-isa-documentation/blob/main/WormholeB0/TensixTile/TensixCoprocessor/SFPMAD.md#ieee754-conformance--divergence" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">github.com/tenstorrent/tt-isa-</span><span class="invisible">documentation/blob/main/WormholeB0/TensixTile/TensixCoprocessor/SFPMAD.md#ieee754-conformance--divergence</span></a></p><p><a href="https://mast.hpc.social/tags/RVV" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>RVV</span></a> <a href="https://mast.hpc.social/tags/SIMD" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>SIMD</span></a> <a href="https://mast.hpc.social/tags/HPC" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>HPC</span></a></p>
Vassil Nikolov | Васил Николов<p><span class="h-card" translate="no"><a href="https://gamerplus.org/@screwlisp" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>screwlisp</span></a></span></p><p>P.S. See also<br>(rational 0.1d0)<br>(rationalize 0.1d0)<br>etc.<br>And `integer-decode-float' is worth its weight in gold when trying to find the _exact_ value of a floating-point number.</p><p><a href="https://ieji.de/tags/CommonLisp" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>CommonLisp</span></a><br><a href="https://ieji.de/tags/FloatingPoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FloatingPoint</span></a></p>
Hacker News<p>When good pseudorandom numbers go bad</p><p><a href="https://blog.djnavarro.net/posts/2025-05-18_multivariate-normal-sampling-floating-point/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">blog.djnavarro.net/posts/2025-</span><span class="invisible">05-18_multivariate-normal-sampling-floating-point/</span></a></p><p><a href="https://mastodon.social/tags/HackerNews" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>HackerNews</span></a> <a href="https://mastodon.social/tags/pseudorandomnumbers" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>pseudorandomnumbers</span></a> <a href="https://mastodon.social/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a> <a href="https://mastodon.social/tags/multivariatenormal" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>multivariatenormal</span></a> <a href="https://mastodon.social/tags/sampling" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>sampling</span></a> <a href="https://mastodon.social/tags/technews" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>technews</span></a> <a href="https://mastodon.social/tags/cybersecurity" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>cybersecurity</span></a></p>
N-gated Hacker News<p>🚀 Ah, the noble <a href="https://mastodon.social/tags/quest" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>quest</span></a> <a href="https://mastodon.social/tags/for" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>for</span></a> "perfect" random floating-point numbers, yet somehow it reads like a 16-minute sleep-inducing lullaby about dividing by zero. 🤔 Who knew the real challenge was turning integers into fractions without losing brain cells in the process? 🙃<br><a href="https://specbranch.com/posts/fp-rand/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">specbranch.com/posts/fp-rand/</span><span class="invisible"></span></a> <a href="https://mastodon.social/tags/randomNumbers" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>randomNumbers</span></a> <a href="https://mastodon.social/tags/perfection" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>perfection</span></a> <a href="https://mastodon.social/tags/floatingPoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingPoint</span></a> <a href="https://mastodon.social/tags/math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>math</span></a> <a href="https://mastodon.social/tags/humor" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>humor</span></a> <a href="https://mastodon.social/tags/HackerNews" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>HackerNews</span></a> <a href="https://mastodon.social/tags/ngated" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>ngated</span></a></p>
Hacker News<p>Perfect Random Floating-Point Numbers</p><p><a href="https://specbranch.com/posts/fp-rand/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">specbranch.com/posts/fp-rand/</span><span class="invisible"></span></a></p><p><a href="https://mastodon.social/tags/HackerNews" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>HackerNews</span></a> <a href="https://mastodon.social/tags/PerfectRandomFloatingPointNumbers" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>PerfectRandomFloatingPointNumbers</span></a> <a href="https://mastodon.social/tags/FloatingPoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FloatingPoint</span></a> <a href="https://mastodon.social/tags/Math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Math</span></a> <a href="https://mastodon.social/tags/RandomNumbers" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>RandomNumbers</span></a> <a href="https://mastodon.social/tags/Technology" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Technology</span></a></p>
Bill the Lizard<p>Is floating point math broken? <a href="https://hachyderm.io/tags/math" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>math</span></a> <a href="https://hachyderm.io/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a> <a href="https://stackoverflow.com/q/588004/1288" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">stackoverflow.com/q/588004/128</span><span class="invisible">8</span></a></p>
R.L. Dane :Debian: :OpenBSD: 🍵 :MiraLovesYou:<p><a href="https://polymaths.social/tags/bash" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Bash</span></a>'s <code>printf</code> supports <code>%f</code>, but bash itself doesn't support <a href="https://polymaths.social/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FloatingPoint</span></a> math...</p><p><a href="https://polymaths.social/tags/thingsthatmakeyougohmm" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>ThingsThatMakeYouGoHmm</span></a></p>
IT News<p>Using Integer Addition to Approximate Float Multiplication - Once the domain of esoteric scientific and business computing, floating point calc... - <a href="https://hackaday.com/2025/04/10/using-integer-addition-to-approximate-float-multiplication/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">hackaday.com/2025/04/10/using-</span><span class="invisible">integer-addition-to-approximate-float-multiplication/</span></a> <a href="https://schleuss.online/tags/softwaredevelopment" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>softwaredevelopment</span></a> <a href="https://schleuss.online/tags/softwarehacks" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>softwarehacks</span></a> <a href="https://schleuss.online/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a> <a href="https://schleuss.online/tags/fpu" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>fpu</span></a> <a href="https://schleuss.online/tags/gpu" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>gpu</span></a></p>
Pyrzout :vm:<p>Using Integer Addition to Approximate Float Multiplication <a href="https://hackaday.com/2025/04/10/using-integer-addition-to-approximate-float-multiplication/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">hackaday.com/2025/04/10/using-</span><span class="invisible">integer-addition-to-approximate-float-multiplication/</span></a> <a href="https://social.skynetcloud.site/tags/SoftwareDevelopment" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>SoftwareDevelopment</span></a> <a href="https://social.skynetcloud.site/tags/SoftwareHacks" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>SoftwareHacks</span></a> <a href="https://social.skynetcloud.site/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a> <a href="https://social.skynetcloud.site/tags/FPU" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FPU</span></a> <a href="https://social.skynetcloud.site/tags/gpu" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>gpu</span></a></p>
Matthias Kretz | Vir<p>Given</p><p>float max = numeric_limits<float>::max();<br>float x = max * max - max * max;</p><p>What is the value of x?</p><p><a href="https://floss.social/tags/cpp" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>cpp</span></a> <a href="https://floss.social/tags/CPlusPlus" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>CPlusPlus</span></a> <a href="https://floss.social/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a></p>
Matthias Kretz | Vir<p>So, as a follow-up to signed zeros in complex numbers: Consider a+b, a-b, 1/a+1/b, 1/a-1/b where a and b are 0. or -0. Some obvious ones:<br>0. + 0. -> 0.<br>1/0. + 1/0. -> inf<br>1/0. + 1/-0. -> NaN<br>-0. - 0. -> -0.<br>But what is 0. + -0. and 0. - 0.?</p><p><a href="https://floss.social/tags/C" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>C</span></a> <a href="https://floss.social/tags/CPlusPlus" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>CPlusPlus</span></a> <a href="https://floss.social/tags/cpp" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>cpp</span></a> <a href="https://floss.social/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a></p>
Pyrzout :vm:<p>How Hard is it to Write a Calculator App? <a href="https://hackaday.com/2025/02/16/how-hard-is-it-to-write-a-calculator-app/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">hackaday.com/2025/02/16/how-ha</span><span class="invisible">rd-is-it-to-write-a-calculator-app/</span></a> <a href="https://social.skynetcloud.site/tags/SoftwareDevelopment" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>SoftwareDevelopment</span></a> <a href="https://social.skynetcloud.site/tags/floatingpoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>floatingpoint</span></a> <a href="https://social.skynetcloud.site/tags/mathematics" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mathematics</span></a></p>
Marc B. Reynolds<p>FWIW: There's a freely available 2023 paper that's basically "Cliff notes" of the book "Handbook of Floating-point Arithmetic"</p><p><a href="https://hal.science/hal-04095151v1" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">hal.science/hal-04095151v1</span><span class="invisible"></span></a></p><p><a href="https://mastodon.gamedev.place/tags/FloatingPoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FloatingPoint</span></a></p>
Marc B. Reynolds<p>Another <a href="https://mastodon.gamedev.place/tags/FloatingPoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FloatingPoint</span></a> refinement of pair arithmetic. This time on the so-called "sloppy add"</p><p><a href="https://arxiv.org/abs/2404.05948" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">arxiv.org/abs/2404.05948</span><span class="invisible"></span></a></p><p>AFAIK: The latest refinement of the accurate building blocks are in this:</p><p><a href="https://hal.science/hal-02972245" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">hal.science/hal-02972245</span><span class="invisible"></span></a></p><p>And there's also weakened constraint versions by Rump & Lang</p><p><a href="https://www.tuhh.de/ti3/paper/rump/LaRu2017b.pdf" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://www.</span><span class="ellipsis">tuhh.de/ti3/paper/rump/LaRu201</span><span class="invisible">7b.pdf</span></a></p>
davinov 👨💻🏳️🌈<p>TC39: Decimal: 0.1+0.2===0.3<br>"Yeahhhh, I don't need to explain much about this proposal"<br>😂<br><a href="https://mamot.fr/tags/JavaScript" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>JavaScript</span></a> <a href="https://mamot.fr/tags/FOSDEM" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FOSDEM</span></a> <a href="https://mamot.fr/tags/FloatingPoint" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FloatingPoint</span></a></p>
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