Re: [Caml-list] Bigarray map & set/get (long)

[Oleg <oleg_inconnu@myrealbox.com>]

On Friday 19 July 2002 09:59 am, Christophe TROESTLER wrote:
> let mac out a b c =
>   for i = 1 to Array2.dim1 a do
>     for j = 1 to Array2.dim2 a do
>       out.{i,j} <- a.{i,j} +. b.{i,j} *. c.{i,j}
>     done
>   done;
>   out

Chris, 

If you are using fortran layout (column-major) why are you incrementing rows 
in the inner-most loop? (AFAICR this can make a big difference with GCC, 
perhaps O'Caml too). Also, each loop seems to contain a call to function 
Array2.dim2. Can't this number be cached? Thirdly, does bigarray access check 
bounds? Can this be turned off? And finally, you might try to experiment with 
0-based indexing [1], it may turn out to be faster.

HTH
Let me/us know how this turns out,
Oleg

[1] I absolutely abhor 0-based indexing in most modern languages
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