haskell - 并行矩阵乘法

Question

我使用 par 编写了一个简单的并行矩阵乘法和 pseq .

运行此程序后，没有任何 Spark 转换(SPARKS:20(0 转换，0 修剪))。

我想听听您对改进这个程序的评论。

还有关于在 Haskell 中学习并行编程的方法。

import Data.List
import Control.Parallel

parHelp :: ( Num a ) => [ a ] -> [ a ] -> a 
parHelp [] [] = 0
parHelp ( x : xs ) ( y : ys ) = ret where 
ret = par a ( pseq b ( a + b ) ) where 
        a = x * y 
        b = parHelp xs ys

helpMult :: ( Num a ) => [ a ] -> [ [ a ] ] -> [ a ]
helpMult _ [] = [] 
helpMult x ( y : ys ) = ret where 
 ret =  par a ( pseq b  ( a : b ) ) where 
   a = sum . zipWith ( *) x $ y  
   b = helpMult x ys

mult :: ( Num a ) => [ [ a ] ] -> [ [ a ] ] -> [ [ a ] ]
mult [] _ = []  
mult ( x : xs ) ys = ret where 
 ret = par a ( pseq b  ( a : b ) ) where 
    a = helpMult x ys 
    b = mult xs ys

main = print $ mult [[1 .. 4 ] , [ 1 .. 4 ] , [ 1 .. 4 ] , [ 1 .. 4] ] ( transpose [[1 .. 4 ] , [ 1 .. 4 ] , [ 1 .. 4 ] , [ 1 .. 4] ])

Answer 1

您是否尝试过非常大(至少 1000 x 1000)的矩阵？计算可能太短而无法并行化。