Re: [Haskell-cafe] ANN: fixed-vector
On 11/12/12 07:05, Aleksey Khudyakov wrote:
>> I have a lot of one-off code where I've defined these myself. Is it
>> possible to e.g. define vectors in R^2 and R^3, and write the p-norm
>> functions only once?
>>
>
> Yes. it's possible.
>
>> {-# LANGUAGE TypeFamilies #-}
>> {-# LANGUAGE FlexibleInstances #-}
>> {-# LANGUAGE MultiParamTypeClasses #-}
>> import Data.Vector.Fixed as V
>> import Data.Vector.Fixed.Internal
>> -- ^^^ Needed for Fun /will be reexported from Data.Vector.Fixed
>> import Data.Vector.Fixed.Unboxed
>
> First we need to define data types and instances. It's possible to use
> vectors from library
>
> ...
Thanks, this looks like exactly what I need. I'll try to replace my R^2
and R^3 implementations the next time I do my homework before the last
minute.
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Re: [Haskell-cafe] ANN: fixed-vector
On 11/12/12 01:57, Carter Schonwald wrote: > Michael, I think that calls for a type-class! > (though I imagine theres a slicker way of writing it) > I'm already using typeclasses, but there's still a bit of boilerplate. I could probably think of something more clever myself, but like I said, these are just one-off experiments, and I'm lazy. So I'm hoping fixed-vector will do it for me! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: fixed-vector
> I have a lot of one-off code where I've defined these myself. Is it
> possible to e.g. define vectors in R^2 and R^3, and write the p-norm
> functions only once?
>
Yes. it's possible.
> {-# LANGUAGE TypeFamilies #-}
> {-# LANGUAGE FlexibleInstances #-}
> {-# LANGUAGE MultiParamTypeClasses #-}
> import Data.Vector.Fixed as V
> import Data.Vector.Fixed.Internal
> -- ^^^ Needed for Fun /will be reexported from Data.Vector.Fixed
> import Data.Vector.Fixed.Unboxed
First we need to define data types and instances. It's possible to use
vectors from library
> data Vec2D a = Vec2D a a
>
> type instance Dim Vec2D = S (S Z)
>
> instance Vector Vec2D a where
> inspect (Vec2D x y) (Fun f) = f x y
> construct = Fun Vec2D
>
>
> data Vec3D a = Vec3D a a a
>
> type instance Dim Vec3D = S (S (S Z))
>
> instance Vector Vec3D a where
> inspect (Vec3D x y z) (Fun f) = f x y z
> construct = Fun Vec3D
>
Now we can define generic p-norm. Maybe you had something different in
mind but still it's function which will work with any vector of fixed
length.
> pNorm :: (Vector v a, Floating a) => a -> v a -> a
> pNorm p = (** recip p) . V.sum . V.map ((** p) . abs)
We will get folloiwng in GHCi:
*Main> pNorm 1 $ Vec2D 1 2 :: Double
3.0
*Main> pNorm 1 $ Vec3D 1 2 3 :: Double
6.0
It's possible to avoid defining data types and use generic vectors
from library. Vec2 is synonym to Data.Vector.Fixed.Unboxed.Vec (S (S Z))
*Main> pNorm 2 (vec $ con |> 1 |> 2 :: Vec2 Double)
2.23606797749979
At the moment their construction is a bit cumbersome
so used replicate to illustrate other vector sizes.
*Main> pNorm 1 (V.replicate 1 :: Vec2 Double)
2.0
*Main> pNorm 1 (V.replicate 1 :: Vec (S (S (S Z))) Double)
3.0
*Main> pNorm 1 (V.replicate 1 :: Vec (S (S (S (S Z Double)
4.0
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Re: [Haskell-cafe] ANN: fixed-vector
Michael, I think that calls for a type-class! (though I imagine theres a slicker way of writing it) On Sun, Nov 11, 2012 at 11:18 PM, Michael Orlitzky wrote: > On 11/10/2012 06:59 AM, Aleksey Khudyakov wrote: > > Hello cafe! > > > > I want to announce library for the small vectors of fixed length > > fixed-vector[1]. Fixed means that vector's length is determined > > by its type. > > > > Generic API can work with both ATD-based vector like complex or > > Vec written below and array-based ones. > > > >> data Vec a = Vec a a a > > > > It's based on post by Roman Leschinsiy[2]. > > > > > > Library also provide array-based vectors with memory > > representation similar to onves from vector package. It's more > > compact though because there is no need to store lengh and and > > offset to first element. > > > > [1] http://hackage.haskell.org/package/fixed-vector > > [2] > http://unlines.wordpress.com/2010/11/15/generics-for-small-fixed-size-vectors/ > > > I have a lot of one-off code where I've defined these myself. Is it > possible to e.g. define vectors in R^2 and R^3, and write the p-norm > functions only once? > > ___ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: fixed-vector
On 11/10/2012 06:59 AM, Aleksey Khudyakov wrote: > Hello cafe! > > I want to announce library for the small vectors of fixed length > fixed-vector[1]. Fixed means that vector's length is determined > by its type. > > Generic API can work with both ATD-based vector like complex or > Vec written below and array-based ones. > >> data Vec a = Vec a a a > > It's based on post by Roman Leschinsiy[2]. > > > Library also provide array-based vectors with memory > representation similar to onves from vector package. It's more > compact though because there is no need to store lengh and and > offset to first element. > > [1] http://hackage.haskell.org/package/fixed-vector > [2] > http://unlines.wordpress.com/2010/11/15/generics-for-small-fixed-size-vectors/ I have a lot of one-off code where I've defined these myself. Is it possible to e.g. define vectors in R^2 and R^3, and write the p-norm functions only once? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
