Re: [julia-users] Re: Setting min()=Inf and max()=-Inf

[Stefan Karpinski]

The decision here was made to be consistent across types: since most types
don't have a way of representing ± infinite values, there's no general way
to do this. It's a bit too much of a subtle corner case to make this work,
but *only* for arrays of concrete floating-point types. Imagine you write
some code and notice that you're only ever putting moderately-sized integer
values into your array before you take its maximum. With the current
arrangement, you can safely change the type of the array to `Int` and
everything will work the same as before. It's one of these cases where
there is no perfect answer.

On Wed, Apr 13, 2016 at 3:30 AM, Niclas Wiberg 
wrote:

> What about minimum() and maximum() with empty floating-point arrays? Would
> it make sense for those to return -Inf and +Inf by default?
>
> I get:
>
> *julia> **a = Array(Float64,(0,))*
>
> *0-element Array{Float64,1}*
>
>
> *julia> **minimum(a)*
>
> *ERROR: ArgumentError: reducing over an empty collection is not allowed*
>
> * in _mapreduce at reduce.jl:139*
>
> * in minimum at reduce.jl:325*
>
>
> Niclas
>
>
>
> Den onsdag 13 april 2016 kl. 09:03:57 UTC+2 skrev Milan Bouchet-Valat:
>>
>> Le mardi 12 avril 2016 à 20:21 -0700, Anonymous a écrit :
>> > Those are good points, although I always kind of wondered why Float
>> > gets Inf while Int doesn't, I guess there's no way to have Inf belong
>> > to 2 distinct concrete types.
>> The problem is that native integers have no way of representing
>> infinite values, contrary to floating point. They can only store actual
>> values. (But you can use floating point formats to store integer data
>> if you need Inf.)
>>
>>
>> Regards
>>
>> > >
>> > > > Have the Julia developers considered the effects of setting
>> > > > Base.min()=Inf and Base.max()=-Inf.  This is common in real
>> > > > analysis since it plays nice with set theory, i.e.
>> > > >
>> > > It only plays nicely with sets of real numbers.  What about sets of
>> > > other types that have a total ordering?  e.g. strings?
>> > >
>> > > Also, one of the general principles guiding the design of the Julia
>> > > standard library is to provide idioms that don't cause types to
>> > > change arbitrarily underneath the user; this principle is critical
>> > > to being able to use the standard library in high-performance code
>> > > (since type stability is critical to compiler optimization).  For
>> > > example min(1,2) == 1 (an Int), min(1) == 1 (an Int), but then
>> > > min() = Inf (floating-point)?
>> > >
>>
>

Re: [julia-users] Re: Setting min()=Inf and max()=-Inf

[Niclas Wiberg]

What about minimum() and maximum() with empty floating-point arrays? Would 
it make sense for those to return -Inf and +Inf by default?

I get:

*julia> **a = Array(Float64,(0,))*

*0-element Array{Float64,1}*


*julia> **minimum(a)*

*ERROR: ArgumentError: reducing over an empty collection is not allowed*

* in _mapreduce at reduce.jl:139*

* in minimum at reduce.jl:325*


Niclas



Den onsdag 13 april 2016 kl. 09:03:57 UTC+2 skrev Milan Bouchet-Valat:
>
> Le mardi 12 avril 2016 à 20:21 -0700, Anonymous a écrit : 
> > Those are good points, although I always kind of wondered why Float 
> > gets Inf while Int doesn't, I guess there's no way to have Inf belong 
> > to 2 distinct concrete types. 
> The problem is that native integers have no way of representing 
> infinite values, contrary to floating point. They can only store actual 
> values. (But you can use floating point formats to store integer data 
> if you need Inf.) 
>
>
> Regards 
>
> > > 
> > > > Have the Julia developers considered the effects of setting 
> > > > Base.min()=Inf and Base.max()=-Inf.  This is common in real 
> > > > analysis since it plays nice with set theory, i.e. 
> > > > 
> > > It only plays nicely with sets of real numbers.  What about sets of 
> > > other types that have a total ordering?  e.g. strings? 
> > > 
> > > Also, one of the general principles guiding the design of the Julia 
> > > standard library is to provide idioms that don't cause types to 
> > > change arbitrarily underneath the user; this principle is critical 
> > > to being able to use the standard library in high-performance code 
> > > (since type stability is critical to compiler optimization).  For 
> > > example min(1,2) == 1 (an Int), min(1) == 1 (an Int), but then 
> > > min() = Inf (floating-point)? 
> > > 
>

Re: [julia-users] Re: Setting min()=Inf and max()=-Inf

[Milan Bouchet-Valat]

Le mardi 12 avril 2016 à 20:21 -0700, Anonymous a écrit :
> Those are good points, although I always kind of wondered why Float
> gets Inf while Int doesn't, I guess there's no way to have Inf belong
> to 2 distinct concrete types.
The problem is that native integers have no way of representing
infinite values, contrary to floating point. They can only store actual
values. (But you can use floating point formats to store integer data
if you need Inf.)


Regards

> > 
> > > Have the Julia developers considered the effects of setting
> > > Base.min()=Inf and Base.max()=-Inf.  This is common in real
> > > analysis since it plays nice with set theory, i.e.
> > > 
> > It only plays nicely with sets of real numbers.  What about sets of
> > other types that have a total ordering?  e.g. strings?
> > 
> > Also, one of the general principles guiding the design of the Julia
> > standard library is to provide idioms that don't cause types to
> > change arbitrarily underneath the user; this principle is critical
> > to being able to use the standard library in high-performance code
> > (since type stability is critical to compiler optimization).  For
> > example min(1,2) == 1 (an Int), min(1) == 1 (an Int), but then
> > min() = Inf (floating-point)?
> > 

[julia-users] Re: Setting min()=Inf and max()=-Inf

[Anonymous]

Those are good points, although I always kind of wondered why Float gets 
Inf while Int doesn't, I guess there's no way to have Inf belong to 2 
distinct concrete types.

On Tuesday, April 12, 2016 at 8:08:19 PM UTC-7, Steven G. Johnson wrote:
>
>
>
> On Tuesday, April 12, 2016 at 10:22:10 PM UTC-4, Anonymous wrote:
>>
>> Have the Julia developers considered the effects of setting 
>> Base.min()=Inf and Base.max()=-Inf.  This is common in real analysis since 
>> it plays nice with set theory, i.e.
>>
>
> It only plays nicely with sets of real numbers.  What about sets of other 
> types that have a total ordering?  e.g. strings?
>
> Also, one of the general principles guiding the design of the Julia 
> standard library is to provide idioms that don't cause types to change 
> arbitrarily underneath the user; this principle is critical to being able 
> to use the standard library in high-performance code (since type stability 
> is critical to compiler optimization).  For example min(1,2) == 1 (an Int), 
> min(1) == 1 (an Int), but then min() = Inf (floating-point)?
>

[julia-users] Re: Setting min()=Inf and max()=-Inf

[Steven G. Johnson]

On Tuesday, April 12, 2016 at 10:22:10 PM UTC-4, Anonymous wrote:
>
> Have the Julia developers considered the effects of setting Base.min()=Inf 
> and Base.max()=-Inf.  This is common in real analysis since it plays nice 
> with set theory, i.e.
>

It only plays nicely with sets of real numbers.  What about sets of other 
types that have a total ordering?  e.g. strings?

Also, one of the general principles guiding the design of the Julia 
standard library is to provide idioms that don't cause types to change 
arbitrarily underneath the user; this principle is critical to being able 
to use the standard library in high-performance code (since type stability 
is critical to compiler optimization).  For example min(1,2) == 1 (an Int), 
min(1) == 1 (an Int), but then min() = Inf (floating-point)?

[julia-users] Re: Setting min()=Inf and max()=-Inf

[Anonymous]

Hi Eric,

Yes that's what I've currently done for a package I'm developing, I was 
just wondering if this was ever considered as being the default setting, 
and if the creators decided not to do it because it doesn't play nice with 
some other aspect of Julia.

On Tuesday, April 12, 2016 at 7:30:23 PM UTC-7, Eric Forgy wrote:
>
> Hi Anonymous,
>
> One of the nice things about Julia is that if you want that feature in 
> your code, you just need to do this:
>
> import Base: min, max
>
> min() = Inf
> max() = -Inf
>
> Voila. It will be a good/fast as if it was in Base (because it is now - 
> for you and anyone using your package) :)
>
> I hope this helps.
>
> Best regards,
> Eric
>
> On Wednesday, April 13, 2016 at 10:22:10 AM UTC+8, Anonymous wrote:
>>
>> Have the Julia developers considered the effects of setting 
>> Base.min()=Inf and Base.max()=-Inf.  This is common in real analysis since 
>> it plays nice with set theory, i.e.
>>
>> A ⊆ B  =>  max(A) ≤ max(B)
>>
>> A ⊆ B  =>  min(A) ≥ min(B)
>>
>> Thus since the empty set ø is a subset of every set, the max of it 
>> should be smaller than the maximum of any nonempty set, and the min of it 
>> should be larger than the minimum of any nonempty set.
>>
>

[julia-users] Re: Setting min()=Inf and max()=-Inf

[Eric Forgy]

Hi Anonymous,

One of the nice things about Julia is that if you want that feature in your 
code, you just need to do this:

import Base: min, max

min() = Inf
max() = -Inf

Voila. It will be a good/fast as if it was in Base (because it is now - for 
you and anyone using your package) :)

I hope this helps.

Best regards,
Eric

On Wednesday, April 13, 2016 at 10:22:10 AM UTC+8, Anonymous wrote:
>
> Have the Julia developers considered the effects of setting Base.min()=Inf 
> and Base.max()=-Inf.  This is common in real analysis since it plays nice 
> with set theory, i.e.
>
> A ⊆ B  =>  max(A) ≤ max(B)
>
> A ⊆ B  =>  min(A) ≥ min(B)
>
> Thus since the empty set ø is a subset of every set, the max of it should 
> be smaller than the maximum of any nonempty set, and the min of it should 
> be larger than the minimum of any nonempty set.
>