Le dimanche 25 mai 2014 08:29:02 UTC+2, James Crist a écrit :
>
> I've been struggling with this for a while, and haven't found a way to do
> it that I'm happy with. I'm sure there is one though. Basically, I want to
> declare a function that works on an array of floats. Doesn't matter what
> kind of float. Doesn't matter if there are 2 different kinds of float
> arrays.
>
> For example, if `a` is an array of Float64, and `b` is an array of
> Float32, the function foobar(a, b) should work, just as well as f(a, a) or
> f(b, b). I've gotten a couple ways to work, but am not sure what's the most
> Julian, and have to believe there is a better way:
>
> 1.) Parametric definition. This gets really long if there are multiple
> different Matrices in the call.
> function foobar{T<:FloatingPoint, S<:FloatingPoint}(a::Matrix{T}, b::
> Matrix{S})
>
>
There seems to be an inconsistency with type definition:
function foo(a::FloatingPoint, b::FloatingPoint)
return a+b
end
or with explicit promotion:
function foo(a::FloatingPoint, b::FloatingPoint)
a, b = promote(a, b)
return a+b
end
are working well.
As well,
x = convert(Array{Float16}, rand(2))
x + rand(2)
is working ok (explicit promotion can also be done).
This would gracefully solve your problem.
But,
function foo(a::Array{FloatingPoint}, b::Array{FloatingPoint})
a + b
end
is unfortunately not working. I don't know whether this is a bug or a
choice.
If you don't care about the specific type of input data, you can directly
specify a::Matrix{FloatingPoint} and b::Matrix{FloatingPoint}
> 2.) Type union definition. Not sure if this is optimal or not. It also
> will only work with the initial defined floats, so anything that subtypes
> FloatingPoint later on will not be valid
> FloatArrays = Union(Matrix{Float16}, Matrix{Float32}, Matrix{Float64})
>
> function foobar(a::FloatArrays, b::FloatArrays)
>
> Am I making this problem more complicated than it needs to be? What is the
> correct way to do this?
>
Just keep in mind that type promotion is not that cheap. This might be
perfectly fine in your workflow or even done on purpose though so don't pay
too much attention to this comment.
