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@aslakhellesoy
Created August 9, 2011 16:18
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Rounding up and down to nearest multiple
/** round n down to nearest multiple of m */
long roundDown(long n, long m) {
return n >= 0 ? (n / m) * m : ((n - m + 1) / m) * m;
}
/** round n up to nearest multiple of m */
long roundUp(long n, long m) {
return n >= 0 ? ((n + m - 1) / m) * m : (n / m) * m;
}
@eoftedal
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eoftedal commented Aug 9, 2011

It seems roundUp is the inverse of roundDown so roundUp could be:
-1 * roundDown(-n, m)
Not sure that makes things clearer though

@aslakhellesoy
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Author

Who cares about clarity for this kind of code! It's just compact math :-) I'll do that refactoring tomorrow. Well spotted!

@jpillora
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jpillora commented Oct 7, 2012

👍

@diogoko
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diogoko commented May 24, 2018

Note that this code only works if all values are integer/long (using float/double gives wrong results in some cases).

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