[erlang-questions] Flooring integer division in Erlang?
Igor Ribeiro Sucupira
<>
Sun Apr 27 09:28:05 CEST 2008
Hum... I see.
Maybe this other implementation?
floorDiv(A, B) ->
case ((A < 0 andalso B >= 0) orelse (A >= 0 andalso B < 0))
andalso A rem B =/= 0 of
true -> (A div B) - 1;
false -> A div B
end.
On Sat, Apr 26, 2008 at 11:06 PM, Dimitry Golubovsky
<> wrote:
> Igor,
>
> Thanks for the suggestion, but it does not work as needed with large
> numbers. I tried similar things just like floor(A/B) (floor/1 was
> found somewhere on TrapExit).
>
> Say we want to print a factorial of 40. Each digit is obtained by
> taking a quot and rem from division by 10. What I compute is
> equivalent to (show . fac) in Haskell
>
> With your function instead of div, in Haskell compiled to Erlang:
>
> 11> hserl:hslist((hserl:force(hs_test1:main()))(40)).
> "815915283247897600060660666066242068688062066800"
>
> Same in ghci:
>
> Prelude> let fac 1 = 1; fac n = n * fac (n - 1)
> Prelude> (show . fac) 40
> "815915283247897734345611269596115894272000000000"
>
> And when I use the standard div, in Haskell compiled to Erlang:
>
> 13> hserl:hslist((hserl:force(hs_test1:main()))(40)).
> "815915283247897734345611269596115894272000000000"
>
> Thanks.
>
>
> On Sat, Apr 26, 2008 at 7:59 PM, Igor Ribeiro Sucupira <> wrote:
> > You could use, for example, the BIF trunc/1.
> > Something like this:
> >
> > floorDiv(A, B) ->
> > Quotient = A / B,
> > Truncated = trunc(Quotient),
> > case Truncated > Quotient of
> > true -> Truncated - 1;
> > false -> Truncated
> > end.
> >
> >
> --
>
>
> Dimitry Golubovsky
>
> Anywhere on the Web
>
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