A-M baby

Task/Matrix-multiplication/Haskell/matrix-multiplication-1.hs

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+import Data.List
+
+ mmult :: Num a => [[a]] -> [[a]] -> [[a]]
+ mmult a b = [ [ sum $ zipWith (*) ar bc | bc <- (transpose b) ] | ar <- a ]
+
+ -- Example use:
+ test = [[1, 2],
+         [3, 4]] `mmult` [[-3, -8, 3],
+                          [-2,  1, 4]]

Task/Matrix-multiplication/Haskell/matrix-multiplication-2.hs

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+import Data.Array
+
+ mmult :: (Ix i, Num a) => Array (i,i) a -> Array (i,i) a -> Array (i,i) a
+ mmult x y
+   | x1 /= y0 || x1' /= y0'  = error "range mismatch"
+   | otherwise               = array ((x0,y1),(x0',y1')) l
+   where
+     ((x0,x1),(x0',x1')) = bounds x
+     ((y0,y1),(y0',y1')) = bounds y
+     ir = range (x0,x0')
+     jr = range (y1,y1')
+     kr = range (x1,x1')
+     l  = [((i,j), sum [x!(i,k) * y!(k,j) | k <- kr]) | i <- ir, j <- jr]