I didn't know Float64 and Float32 are the same on 32-bit systems. Thanks.
On Monday, 25 August 2014 15:48:30 UTC-4, Tobias Knopp wrote:
>
> Thats for a reason. Float64 and Float32 are the same on 64 and 32 bit
> computers. Its only the integer types where this matters.
>
> Am Montag, 25. August 2014 21:38:44 UTC+2 schrieb Roy Wang:
>>
>> Thanks Tom. Pweh, that's what I suspected.
>>
>> I glanced at boot.jl, and it doesn't seem Julia has a typealias for
>> doubles. I'll define my own to check for 32 vs. 64-bit systems.
>>
>> On Monday, 25 August 2014 15:10:30 UTC-4, Tomas Lycken wrote:
>>>
>>> Actually, Int (and UInt) are aliases to the “native size integer”, so
>>> if you specify Int you will get Int32 on a 32-bit system and Int64 on a
>>> 64-bit system. So no, don’t change my_var::Int to my_var::Int32 -
>>> that’ll make your code *worse* on 64-bit systems ;)
>>>
>>> // T
>>>
>>> On Monday, August 25, 2014 9:05:06 PM UTC+2, Roy Wang wrote:
>>>
>>>
>>>> Thanks guys. So to clarify: FloatingPoint is not a concrete types, so
>>>> explicitly defining variables or function inputs using it will not speed
>>>> things up. Instead, I should use Float64, Float32, etc.
>>>>
>>>> Is Int an abstract type as well? I'm wondering if I should go back and
>>>> rename everything my_var::Int to my_var::Int32.
>>>>
>>>> John: I couldn't find the mutate!() function in the Julia Standard
>>>> Library v0.3. Do you mean my own function that mutates the source array?
>>>>
>>>> On Monday, 25 August 2014 14:54:14 UTC-4, Patrick O'Leary wrote:
>>>>>
>>>>> On Monday, August 25, 2014 12:28:00 PM UTC-5, John Myles White wrote:
>>>>>>
>>>>>> Array{FloatingPoint} isn't related to Array{Float64}. Julia's type
>>>>>> system always employs invariance for parametric types:
>>>>>> https://en.wikipedia.org/wiki/Covariance_and_contravariance_(computer_science)
>>>>>>
>>>>>> <https://www.google.com/url?q=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FCovariance_and_contravariance_%28computer_science%29&sa=D&sntz=1&usg=AFQjCNH5Mpuwh71o9dv0_TDx9OcMvvKfWg>
>>>>>>
>>>>>
>>>>> To underline this point a bit, it's even a bit worse than that:
>>>>> Array{FloatingPoint} will work just fine for a lot of things, but it
>>>>> stores
>>>>> all elements as heap pointers, so array-like operations (such as linear
>>>>> algebra routines) will often be extremely slow.
>>>>>
>>>>> As a rule, you almost never use an abstract type as the type parameter
>>>>> of a parametric type for this reason. Where you wish to be generic over a
>>>>> specific family of types under an abstract type, you can use type
>>>>> constraints:
>>>>>
>>>>> function foo{T<:FloatingPoint}(src::Array{T,1})
>>>>> ...
>>>>> end
>>>>>
>>>>> But often type annotations can be omitted completely.
>>>>>
>>>>
>>>
>>
