Converting default Float type to Float32

General Usage Performance
1

I have noticed on my system that whenever I define CuArrays, I get Float64 as default. Is there a way to change the default to Float32, i.e. without specifying the type every time I define CuArrays? I want to get Float32, say, when I am using GPU.

2

Can you give an example of what you mean by default? In Julia, floating point literals are 64-bit. Is that causing the “default” behavior you observe or something else?

1 Like
3

For instance, if I just define

A = CuArray([Inf for i = 1:20])
typeof(A) gives
CuArray{Float64, 1, CUDA.Mem.DeviceBuffer}

unless I do
A=CuArray{Float32}([Inf for i = 1:20])
typeof(A) gives
CuArray{Float32, 1, CUDA.Mem.DeviceBuffer}

I am looking for a way to do
A = CuArray([Inf for i = 1:20])
so that
typeof(A) gives
CuArray{Float32, 1, CUDA.Mem.DeviceBuffer}

Thank you for the response. Sorry, I am new here and I am not sure how I can convert to code formats.

4

If you want Float32 literals you can enter them in scientific notation with f instead of e. For the special case of Inf and NaN there are 32-bit versions with a 32 suffix.

julia> typeof(3.2f0)
Float32

julia> typeof(Inf32)
Float32

julia> typeof(NaN32)
Float32
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5

@GunnarFarneback already answered your question, but to be more explicit, the chain of events you need to understand is the following:

  1. Inf is a Float64 value.
  2. [Inf for i = 1:20] creates an Array{Float64, 1} since each item in the array is a Float64 value.
  3. CuArray([Inf for i = 1:20]) creates a CuArray{Float64, 1, CUDA.Mem.DeviceBuffer} since it’s taking in an Array{Float64, 1}.

Sorry, I am new here

You don’t ever need to apologize for being new.

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6

You might be looking for cu, which copies a Vector{Float64} to a CuArray{Float32, 1, ...}, changing the element type on the assumption that this was just the default, and the GPU default should be Float32 (as Float64 is usually much much slower there).

3 Likes
7

I am not aware of the cu , I would be grateful if you have the link to the same or some minimal working example. Thank you.

8

Thank you everyone for the great suggestions. Just for the reference if anyone should have a similar question in the future I just found out that a similar question was asked on here on the stackoverflow with satisfactory answers.