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luafloating-accuracylove2d

lua decimals break around -0.1 to 0.1 (exclusive)

I have a Lua for loop that iterates through numbers from -1 to 1 by increments of 0.01, and is producing numbers as bad as 6.6613381477509e-016 in the range of -0.1 to 0.1 (exclusive)

I am using Lua in the LOVE engine (v 0.9.2), written in C++

I would much rather solve the problem than just receive an info dump of an explanation, but I'd rather that than nothing at all.

(also I do understand the general reason floats are inaccurate, so that may be left out of explanations)

Solution

  • You've already known the reason, here's a possible solution: don't loop with floating point numbers, use integers.

    Instead of

    for i = -1, 1, 0.01 do

    use:

    for i = -100, 100 do
  print(i / 100)
end