I was trying to use the array comprehension of the Data Parallel
Haskell package.
http://haskell.org/haskellwiki/GHC/Data_Parallel_Haskell
for instance I can define
{-# OPTIONS -fparr -fglasgow-exts #-}
module MatTest
where
import GHC.PArr
ident = [:[:1,0:],[:0,1:]:]
aVect = [:4,5:]
dotP :: Num a => [:a:] -> [:a:] -> a
dotP xs ys = sumP [:x * y | x <- xs | y <- ys :]
matVecMul :: Num a => [:[:a:]:] -> [:a:] -> [:a:]
matVecMul xs ys = [:dotP x ys | x <- xs:]
but when I tried to define a matrix matrix multiplication
matMel :: Num a => [:[:a:]:] -> [:[:a:]:] -> [:a:]
I was at a loss for how to do it because i couldn't define transpose.
On 4/18/07, Henning Thielemann
On Wed, 18 Apr 2007, Chris Witte wrote:
I just started playing around with GHC.PArr and array comprehension and I was wondering if there is a way to define the transpose of a matrix using array comprehension?
Why not
let swap :: (i,j) -> (j,i) swap (a,b) = (b,a) in ixmap (let (lower,upper) = bounds arr in (swap lower, swap upper)) swap arr
?