It seems like div might do exactly what you want, although I'm not sure
what it does behind the scenes.
julia> A = rand(Uint8, (100, 100));
julia> b = div(A, uint8(2))
100x100 Array{Uint8,2}:
...
Also, it seems like it keeps the type of the numerator, no matter the
(integer) type of the denominator. However, if the denominator is a
float it returns floats as well, which to me seems a bit silly since
the results are by definition integers (but I don't know if this really
is an inconsistency).
On Fri, Apr 4, 2014, at 2:54, Carlos Becker wrote:
Thanks Tim, that makes total sense, though I was thinking of a way of
expressing this in a matlab-ish kind of way.
How about defining a macro to override type promotion, similar to
@inbounds?
@nopromote b = A / uint8(2)
I would like something shorter, but we could decide on the exact name
later.
Does this make sense?
------------------------------------------
Carlos
On Fri, Apr 4, 2014 at 11:40 AM, Tim Holy <[1]tim.h...@gmail.com>
wrote:
This doesn't address your bigger question, but for truncating division
by n I
usually use b[i] = div(A[i], convert(eltype(A), n)). For the particular
case
of dividing by 2, an even better choice is b[i] = A[i] >> 1.
--Tim
On Friday, April 04, 2014 02:09:24 AM Carlos Becker wrote:
> I've seen previous posts in this list about this, but either I missed
some
> of them or this particular issue is not addressed. I apologize if it
is the
> former.
>
> I have a Uint8 array and I want to divide (still in Uint8) by 2. This
is
> very handy when dealing with large images: no need to use more memory
than
> needed.
> So, for example:
>
> A = rand(Uint8, (100,100)); # simulated image
>
> b = A / uint8(2)
>
> typeof( b ) # ==> returns Array{Float32,2}
>
>
> I understand why one may want that, but is there a way to override it
and
> do the plain, element-wise uint8-by-uint8 division?
> (ie ignore promotion rules)
>
> Thanks.
References
1. mailto:tim.h...@gmail.com
