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    Replace JS for your favorite language:


    JS just happens be everyone’s favorite punching bag nowadays ;)

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      Most other languages I know of let you specify that a number is an integer ;)

      EDIT: wow this was a very bad brain fart, and I’m leaving it here as a testament to how quickly people will pile on on Javascript without thinking. Sorry everyone.

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        0.1 + 0.2 doesn’t work well for integer math either.

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          Multiple them by enough zeros to turn them into integers. Do the math in integer form for integer rules (1 + 2). Reverse the process to get float results.

          I’ve done that before a long time ago. I can’t remember why I did. Maybe just to dodge floats’ problems during number crunching. I know peoples’ reactions to it were funny.

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            I’m going to point out that COBOL handles this tricky calculation “unsurprisingly” by default. We should all switch from JavaScript to COBOL.

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            Upvoting because the edit is a good example of self-awareness and humility.

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            the author does state:

            This behaviour is not unique to JavaScript. It is seen in every programming language where doubles are available, including C, C++, C#, Erlang, Java, Python and Rust.

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            I very much like the way this blog presented the numbers out in full, that helps to see what’s really going on behind the scenes.

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              It’s actually kind of interesting that you can exactly represent doubles in decimal but you can’t exactly represent decimal numbers as doubles. This is because 2 divides 10 but 10 does not divide 2. So with enough decimal digits, you have enough 2s in the denominator to exactly represent a fractional binary number.

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              [Super Mario 64 menu theme]

              Great and creative way to set the tone!

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                Yeah computers are stupid

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                  Whoever attempts floating-point calculation with JavaScript is, of course, in a state of sin.

                  John von Neumann, probably.

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                    What language should one use for floating point calculations?

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                      TCL, of course, because EIAS!

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                        In most languages there are libraries to deal with precise numbers. For example, you can use Decimal in Python. https://docs.python.org/3/library/decimal.html

                        But it may not be as fast or have other inconveniences (for example, defining explicitly the precision)

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                          There are some good examples in the list @HugoDaniel posted in this thread.

                          Here’s something interesting for JS: http://mikemcl.github.io/decimal.js/

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                            If you want it to work correctly, then probably SPARK, C w/ tooling, or Gappa w/ language of your choosing. If performance isn’t an issue, there’s a pile of languages with arbitrary-precision arithmetic plus libraries for those without it. I’d say that’s the options.

                            Meanwhile, there’s work in formal methods on Exact-Real Arithmetic that could give us new options later. There was an uptick in it in 2018. I’m keeping an distant eye on it.