Re: expected 0 not result gotten

in reply to expected 0 not result gotten

Wise Man Say: “Floating point numbers like little piles of sand. Each time you pick one up and move it around, you lose a little sand and pick up a little dirt.”

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Re^2: expected 0 not result gotten by ikegami (Patriarch) on Dec 22, 2011 at 20:38 UTC
Except that's not quite true. Each time you pick one up and move it around, you may lose a little sand. "Sand" is only lost when the number has a huge (>53) number of digits in binary. This usually happens because of the use of numbers that are periodic in binary; they have an infinite number of digits. The OP used 425/10000 and 25/10000 which are both periodic in binary (like 1/3 is in decimal).	[reply]

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Re^2: expected 0 not result gotten
by ikegami (Patriarch) on Dec 22, 2011 at 20:38 UTC

Except that's not quite true. Each time you pick one up and move it around, you may lose a little sand. "Sand" is only lost when the number has a huge (>53) number of digits in binary.

This usually happens because of the use of numbers that are periodic in binary; they have an infinite number of digits. The OP used 425/10000 and 25/10000 which are both periodic in binary (like 1/3 is in decimal).

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