[Haskell-cafe] Matrices in Haskell

[Vincent Kraeutler]

Claus Reinke wrote:
>> When you tried using Arrays, I presume you used an array indexed by a
>> pair (i,j), and just reversed the order of the index pair to switch from
>> row-wise to column-wise access? It's hard to see how that would slow you
>> down. Perhaps the slowdown was caused by excessive array copying?
>
> the difference can be in locality wrt the memory hierarchy: is the
> next element
> nearby most of the time (apart from array borders), or a
> row-/column-width away most of the time?
>
> i understand that, eg, fortran and c differ in their default
> interpretations of array layout, so naively translated benchmarks
> might suffer from running against the grain in one of the two
> (row-major loops over a column-major layout, or the
> other way round).
>
> claus
>
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>
it seems unlikely to me that this would cause a degradation in
performance with respect to lists...
or is there something very interesting to learn about the inner workings
of linked lists in ghc?

regards,
v.

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