I made a very simple matrix module that implements matrix sum and
multiplication.
It does not require any especific type since it uses Num [[a]]. So
instead of typing something like
Matrix [[1,0],[0,2]] * Matrix [[1,2],[3,4]]
you can just type
[[1,0],[0,2]]*[[1,2],[3,4]]
It needs -fglasgow-exts
Atila
module SimpleMatrix where
instance Num a => Num [[a]] where
fromInteger x = [[fromInteger x]]
abs x = map (map abs) x
(+) [ ] y = y
(+) x [ ] = x
(+) x y = zipWith (zipWith (+)) x y
(*) x y = map (matrixXvector x) y
where
-- matrixXvector :: Num a => [[a]] -> [a] -> [[a]]
matrixXvector m v = foldl vectorsum [] $ zipWith vectorXnumber m v
-- vectorXnumber :: Num a => [a] -> a -> [a]
vectorXnumber v n = map (n*) v
-- vectorsum :: [a] -> [a] -> [a]
vectorsum [] y = y
vectorsum x [] = x
vectorsum x y = zipWith (+) x y
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