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wtf is floating-point-gui.de?

gaearon/floating-point-gui.de — explained in plain English

Analysis updated 2026-07-17 · repo last pushed 2020-01-23

★ 2Audience · developerComplexity · 1/5DormantLicenseSetup · easy

TL;DR

An educational static website explaining why floating-point math gives surprising results like 0.1+0.2=0.30000000000000004, and how to handle it.

Mindmap

mindmap
  root((repo))
    What it does
      Explains float quirks
      Quick answers
      Deep dive material
    Tech stack
      nanoc
      Static HTML
    Use cases
      Debug rounding errors
      Choose a number type
      Learn binary decimals
    Audience
      Beginner coders
      Intermediate coders
    Details
      Static site generator
      Creative Commons license

Code map

Detail Auto

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filefunction / class

Why would anyone build with this?

REASON 1

Look up why a calculation like 0.1 + 0.2 doesn't equal exactly 0.3 in your code.

REASON 2

Read the deeper material to understand how computers store decimals in binary.

REASON 3

Decide whether floating-point, fixed-point, or decimal representation fits your use case.

What's in the stack?

nanoc

How it stacks up

gaearon/floating-point-gui.de0-bingwu-0/live-interpreter0xkaz/llm-governance-dashboard
Stars222
Language—PythonPython
Last pushed2020-01-23——
MaintenanceDormant——
Setup difficultyeasymoderatehard
Complexity1/52/54/5
Audiencedevelopergeneralops devops

Figures from each repo's GitHub metadata at analysis time.

How do you spin it up?

Difficulty · easy Time to first run · 5min

Built with nanoc and published under a Creative Commons license.

Yoink these prompts

Prompt 1
Explain why my code produced 0.30000000000000004 instead of 0.3 and how floating-point storage causes it.
Prompt 2
Help me decide whether to use floating-point or a decimal type for a financial calculation in my app.
Prompt 3
Show me a simple way to safely compare floating-point numbers for equality in my code.

Frequently asked questions

wtf is floating-point-gui.de?

An educational static website explaining why floating-point math gives surprising results like 0.1+0.2=0.30000000000000004, and how to handle it.

Is floating-point-gui.de actively maintained?

Dormant — no commits in 2+ years (last push 2020-01-23).

How hard is floating-point-gui.de to set up?

Setup difficulty is rated easy, with roughly 5min to a first successful run.

Who is floating-point-gui.de for?

Mainly developer.

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