*From*: Philipp Kutin <philipp.kutin@xxxxxxxxx>*To*: luajit@xxxxxxxxxxxxx*Date*: Fri, 31 Aug 2012 13:39:10 +0200

On Thu, Aug 30, 2012 at 6:10 PM, Francesco Abbate <francesco.bbt@xxxxxxxxx> wrote: > I was therefore wondering how to obtain the integer division in > Lua/LuaJIT. Of course it can be done using some tricks: > > c = (a - a % b) / b > > or > > c = math.floor(a / b) Careful there! These two are equivalent, but not the same as C integer division, which is the remainder of a/b assuming truncated division. I think there's no other way than resorting to something like function cdiv(a, b) q = a/b return (q > 0) and math.floor(q) or math.ceil(q) end to simulate C's division for negative divisors or dividends. Here's a nifty comparison of various division rounding methods I found the other day: http://www.cs.uu.nl/~daan/download/papers/divmodnote.pdf --Philipp

**Follow-Ups**:**Re: very simple questions about integer division***From:*Philipp Kutin

**Re: very simple questions about integer division***From:*Pierpaolo Bernardi

**References**:**very simple questions about integer division***From:*Francesco Abbate

- » very simple questions about integer division- Francesco Abbate
- » Re: very simple questions about integer division- Mike Pall
- » Re: very simple questions about integer division - Philipp Kutin
- » Re: very simple questions about integer division- Philipp Kutin
- » Re: very simple questions about integer division- Francesco Abbate
- » Re: very simple questions about integer division- Pierpaolo Bernardi
- » Re: very simple questions about integer division- Mike Pall
- » Re: very simple questions about integer division- Philipp Kutin
- » Re: very simple questions about integer division- Egor Skriptunoff