Why does 4.1% 2 return 0.0999999999999996 using Ruby? But 4.2% 2 == 0.2

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Why does 4.1% 2 return 0.0999999999999996 using Ruby? But 4.2% 2 == 0.2

Why does 4.1% 2 return 0.0999999999999996? But 4.2% 2 == 0.2.

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ruby floating-accuracy

Alex Jan 9 '12 at 12:46

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5 answers

Manuel selva · Answer 1 · 2012-01-09T12:48:09+0000

See here: What Every Programmer Should Know About Floating-Point Arithmetic

Real numbers are endless. Computers work with a finite number of bits (32 bits, 64 bits today). As a result, floating point arithmetic performed by computers cannot represent all real numbers. 0.1 is one of these numbers.

Note that this is not a problem with Ruby, but with all programming languages, because it comes from the way computers represent real numbers.

Michael Kohl · Answer 2 · 2012-01-09T12:49:02+0000

Float , .

Ned Batchelder · Answer 3 · 2012-01-09T13:00:33+0000

: http://docs.python.org/tutorial/floatingpoint.html. Python, , .

Rick Regan · Answer 4 · 2012-01-09T14:23:46+0000

, 4.1 = 4.0999999999999996447286321199499070644378662109375 4.2 = 4.20000000000000017763568394002504646778106689453125. , 4.1 , , 4.2 .

0.20000000000000017... 0,2, 0.099999999999999644... 0,1? Ruby, , 15 .

Oliver Charlesworth · Answer 5 · 2012-01-09T12:47:52+0000

Because you work with a floating point. A floating point binary cannot exactly represent 0.1.

Why does 4.1% 2 return 0.0999999999999996 using Ruby? But 4.2% 2 == 0.2

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