Passing a matrix from C to Haskell

[Cyril Schmidt]

I need to pass a big 2-dimensional array of doubles from a legacy
C code to a Haskell module. Of this huge array, the Haskell code will 
actually use only
a few elements (say, 10 out of 100x20 matrix). Unfortunately, the C code 
does not know
which data are actually needed in the Haskell module.

What would be a good way to pass the array to Haskell and, once the data 
are handed over,
what is the fastest way to fetch these elements?

I was thinking of something like passing the array as Ptr Int#, but how 
do I fetch the elements
that I am interested in?

Cheers,

Cyril