Questions about linear, a Haskell library for linear algebra.
Questions tagged [haskell-linear]
7 questions
7
votes
1 answer
How do I use variable size vectors in Edward Kmett's "Linear" library?
I'm trying to use ekmett's linear library, and I'm having some trouble with variable length vectors, in Linear.V. How do I use the dim function to get the size of a vector? How do I use trace on a large square matrix made of nested Vs ? I get errors…
Christian Oudard
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5
votes
1 answer
How to derive Additive generically on Haskell, without defining an Applicative instance?
Given a type, there is only one obvious way to implement an Additive instance, from the Linear library, to it. Conveniently, Additive has a generic implementation, so we can use deriving for it. Unfortunately, it depends on the existence of an…
MaiaVictor
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5
votes
1 answer
How do you scale a vector using the Haskell library, Linear?
This is a simple question about style. I've been using:
import Linear
point = V3 1 2 3
scaled = fmap (* 2) point
Or...
scaled = (* 2) <$> point
Is this the intended way, or is there a proper multiplication by scalar operator?
MaiaVictor
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3
votes
1 answer
"Linear" package truncating values close to 0 when using `normalize`
I've spent a few minutes debugging a problem that tracked down to "Linear" truncating values that are close to zero when using "Linear.normalize". Specifically, I was taking the cross product of very small triangles and normalizing the result,…
MaiaVictor
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3
votes
0 answers
Optimizing this haskell linear algebra code
I have this Haskell code for testing collisions between shapes (it depends on the linear and lens packages)
import Linear hiding (trace)
import Control.Lens.Getter ((^.))
type Vec3 = V3 Float
data Tri = Tri Vec3 Vec3 Vec3
data Box = Box Vec3…
Dan
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2
votes
0 answers
Haskell Linear + AD, implementing Metric for Forward?
I'm trying to use diff from the ad package on a function Quaternion a -> Quaternion a or more generally Metric a => a -> a relying on quadrance.
I'm not sure what the best way to go about this is, since Forward doesn't have a Metric instance and…
Charles Durham
- 1,707
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0
votes
1 answer
Haskell code won't compile with certain variable names
I'm getting an error from GHCi that I can't explain. I'm working with the following code (the vast majority of which is seemingly-irrelevant to the issue, but I can't replicate the issue with less code; commented-out lines are ones that I would like…
zjs
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