I'm trying to use hmatrix, and hmatrix-gsl-stats. But I am getting absolutely bizarre results. Can anybody reproduce what I'm seeing?
import Numeric.LinearAlgebra
import Numeric.GSL.Fitting.Linear
main :: IO ()
main = do
let y = fromList [1,2,3,4,5]
let x = trans $ fromLists [[1,2,3,4,5], [1,1,1,1,1]]
let x3 = fromLists [[1,1], [2,1], [3,1], [4,1], [5,1]]
print $ x == x3
print $ multifit x y
print $ multifit x3 y
So I just compile this and run it, and I get:
True
(fromList [0.6121951219512196,0.39756097560975645],(2><2)
[ 0.5100317271465397, -0.46568114217727535
, -0.46568114217727535, 0.82048582193139 ],27.27560975609756)
(fromList [1.0000000000000002,-8.881784197001252e-16],(2><2)
[ 2.1364982849735737e-32, -6.40949485492072e-32
, -6.40949485492072e-32, 2.350148113470931e-31 ],6.409494854920721e-31)
Am I missing something totally obvious?
I think this is a problem with how matrix transposition is handled internally. When you call trans, it's just a flipped bit in the metadata... that is apparently not being inspected when passing the matrix through the FFI.
If you try this, multifit (reshape (cols x) $ flatten x) y, on your penultimate line, you can force the transposition.