Lo que todo programador debería saber sobre aritmética de punto flotante
Improve intro comment on rounding error cancels
authored by
Greg Smith
and committed by
Michael Borgwardt
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### Why do other calculations like 0.1 + 0.4 work correctly?
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In that case, the result (0.5) *can* be represented exactly as a floating-point number,
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and the errors in the input numbers cancel each other out.
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and it's possible for rounding errors in the input numbers to cancel each other out.
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Even that can't necessarily be relied upon though. If for example those two numbers
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were stored in differently sized floating point representations first, and then added
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together, the rounding errors might not have offset each other perfectly.
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In other cases like 0.1 + 0.3, the result actually isn't *really* 0.4, but close enough that 0.4
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is the shortest number that is closer to the result than to any other floating-point number. Many languages then display that number instead of converting the actual result back to the closest
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decimal fraction.
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decimal fraction.