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Deeper Explanation of Floating Point Arithmetic Issues

I understand that there can be problems with floating point numbers in JavaScript (and other machine languages); but I don't quite understand how to get around this problem in a best-practice sense. If I can use WolframAlpha and/or a graphing calculator to multiply 0.1 and 0.2 together without getting a weird answer (i.e., 0.020000000000000004), then why can't a computer handle this when using JavaScript? How do I get past this?

2 Answers

Firstly, I think that having a greater scope of what you're trying to do will help others find an answer to this question. Give a specific example of a problem and some context and I'll try to help the best I can.

Let's say that I am comparing variable values in an if(a+b <= 0.3), and, at some point, a = 0.1 and b = 0.2. The condition would result is false (since 0.1 + 0.2 returns 0.30000000000000004), when one would expect (when thinking about arithmetic) the condition to result in true.

There are surely more floating point problems like this, and accuracy of simple math in code is important and shouldn't return semi-erroneous answers.

So, what is the workaround to something like this?

Excellent. That's what I found when I got your response.