nowfound

Life & fun · April 18, 2026

IM

I made a calculator that works over disjoint sets of intervals

I've been studying interval arithmetic for the past few weeks and it's a really interesting field because while there is a ton of super interesting research published over the past decades, it has never really gotten the recognition that it deserves, IMO. One reason for this is that standard interval arithmetic has really poor handling of division by intervals containing zero. If you compute 1 / [-1, 2] in regular interval arithmetic, you get either [-∞, +∞], or you have to say that the operation is undefined. Both solutions are virtually useless. The real answer of course is [-∞, -1] U…

I made a calculator that works over disjoint sets of intervals launched on April 18, 2026 with 314 votes, #64 of 21,248 launches that month and more than 99% of that year's launches.

Visit victorpoughon.github.io ↗Alternativestop 1% of April 2026

In plain words

This is a calculator that performs arithmetic operations on disjoint sets of intervals, addressing a key limitation in standard interval arithmetic. It's designed for mathematicians and researchers studying interval arithmetic who need more precise results when dividing by intervals containing zero. The tool returns unions of disjoint intervals rather than unbounded or undefined results, allowing users to confidently exclude ranges of real numbers from possible outcomes. It's built on interval arithmetic research that the creator believes deserves broader recognition in computational mathematics.

written from the facts on this page · September 2026

From the sources

This is a calculator that works over unions of intervals rather than just real numbers. It is an implementation of Interval Union Arithmetic . An interval [a, b] represents the set of all numbers between and including a and b. An interval union: [a, b] U [c, d] is a disjoint set of intervals. ➤ 2 / [-2, 1] [-∞, -1] U [2, +∞] The interesting thing about interval union arithmetic is the inclusion property, which means that if you pick any real number from every input union and compute the same expression over the reals, the result is guaranteed to be in the output union. ➤ ( [5, 10] U [15, 16] ) / [10, 100] [0.05, 1.6] Operations can result in disjoint unions of intervals: ➤ 1 / [-2, 1] [-∞,…from victorpoughon.github.io

In the maker’s words, at launch

I've been studying interval arithmetic for the past few weeks and it's a really interesting field because while there is a ton of super interesting research published over the past decades, it has never really gotten the recognition that it deserves, IMO. One reason for this is that standard interval arithmetic has…

Does a similar job

all alternatives →
  • AD
    All desktop software calculators are wrong, so I had to build my own2022 · ▲286

    A new calculator software cannot really bring attention (https://chachatelier.fr/chalk/) However, I wrote a full article explaining why I had to build something "new" that does not behave like usual desktop calculator softwares : TL;DR All "small" calculator softwares I know share the same design flaws. And the GUI is not the only stumbling block in their poor efficiency. Handling correctly numerical approximations - expected or not - is crucial to trust the results. It is usually not done in lightweight tools. It should. So I prove that if I could do it, OS manufacturers…

  • I made a web-based notepad with a built in unit calculator2022 · numpad.io · ▲488

    I launched NumPad v1 on here a few years ago, and back then it wasn't much more than a thin CodeMirror wrapper around the calculator engine I'd written. Now I've rewritten it as a PWA that supports multiple documents, persists them to IndexedDB, and has a syncing service for paying customers. Syncing is handled by Automerge[1] under the hood, which should make it relatively easy to get document sharing working too. [1] https://automerge.org/

  • I made a web game that makes practicing basic arithmetic fun2024 · worchle.com · ▲161

    Hey, maker here. After launching a daily word search game, I randomly thought of this math game while driving. Finally got around to making it and I think it turned out pretty cool. It’s a math search game that’s meant to help you practice your quick addition, subtraction, multiplication, and division skills. I’m hoping it’ll help people (even those like me who aren’t big on math) learn and increase their speeds. (There are also some settings you can enable to make the game harder) If you try it out, please let me know if you found it fun, if you have anything you’d like me to add, or if you…

  • IQ
    I quit coding years ago. AI brought me backJan 2026 · calquio.com · ▲314

    Quick background: I used to code. Studied it in school, wrote some projects, but eventually convinced myself I wasn't cut out for it. Too slow, too many bugs, imposter syndrome — the usual story. So I pivoted, ended up as an investment associate at an early-stage angel fund, and haven't written real code in years. Fast forward to now. I'm a Buffett nerd — big believer in compound interest as a mental model for life. I run compound interest calculations constantly. Not because I need to, but because watching numbers grow over 30-40 years keeps me patient when markets get wild. It's basically…

  • I made an interactive math crossword puzzle with infinite levels2024 · scientific.place · ▲165

    Hey there! I'm the brains behind the math crossword game on my site. This game is all about making math a little more fun – users just drag and drop numbers to fill in the blanks and move on to the next level if they get it right. Let me know if face any issues or have any suggestions! :)

  • IM
    I made a spreadsheet where formulas also update backwardsDec 2025 · victorpoughon.github.io · ▲252

    Hello HN! I'm happy to release this project today. It's a bidirectional calculator (hence the name bidicalc). I've been obsessed with the idea of making a spreadsheet where you can update both inputs and outputs, instead of regular spreadsheets where you can only update inputs. Please let me know what you think! Especially if you find bugs or good example use cases.

More life & fun this month

the category →

Source: Show HN post ↗ · launch text quoted in part

Launched alongside, April 2026

the whole month →
  • Brila▲1,364

    One-page websites from real Google Maps reviews

    AI · Apr 2026 · brila.ai

  • AG
    A game where you build a GPU▲964

    Thought the resources for GPU arch were lacking, so here we are

    Life & fun · Apr 2026 · jaso1024.com

  • I built a tiny LLM to demystify how language models work▲915

    Built a ~9M param LLM from scratch to understand how they actually work. Vanilla transformer, 60K synthetic conversations, ~130 lines of PyTorch. Trains in 5 min on a free Colab T4. The fish thinks the meaning of life is food. Fork it and swap the personality for your own character.

    AI · Apr 2026 · github.com

  • Fathom 3.0▲800

    AI meeting notes: now bot-free, in ChatGPT & Claude + more

    AI · Apr 2026 · fathom.ai

  • Brutalist Concrete Laptop Stand (2024)▲786

    I made a laptop stand out of solid concrete, in the style of brutalist architecture, with themes of urbex and urban decay

    Life & fun · Apr 2026 · sam-burns.com

  • I built a frontpage for personal blogs▲783

    With social media and now AI, its important to keep the indie web alive. There are many people who write frequently. Blogosphere tries to highlight them by fetching the recent posts from personal blogs across many categories. There are two versions: Minimal (HN-inspired, fast, static): https://text.blogosphere.app/ Non-minimal: https://blogosphere.app/ If you don't find your blog (or your favorite ones), please add them. I will review and approve it.

    AI · Apr 2026 · text.blogosphere.app