Re: [Bug] math.mod behaves differently than the modulus operator.

[Daniel Stephens <daniel@...>]

Tom Barta wrote:
> On Jan 26, 2008 4:29 PM, Luiz Henrique de Figueiredo
> <lhf@tecgraf.puc-rio.br> wrote:
>   
> > Please don't cry BUG when you see something you don't expect.
> >     
>
> Out of curiosity, is there any explicit reason for math.mod() behaving
> differently than the modulus operator (%)?  It seems counterintuitive
> that they behave differently (despite the lack of a formal guarantee
> by the manual), but maybe I'm overlooking some case where the
> distinction is worthwhile.
>   
They have different behaviors for values where the sign of the value is 
different from the divisor, each can be more or less useful in different 
situations depending on your needs.

For example, Lua's choice of implementation guarantees that a % b == (a 
+ N * b) % b for all integer N, whereas math.mod does not.