Package with multidimensional AND sparse matrices?

["Andreas Biegert" <andreas.biegert@googlemail.com>]

Hi,

I am a bioinformatics student from Germany and OCaml is my language of
choice for my diploma thesis program. So far, everything worked out
great, thanks to OCaml allowing for short development cycles. However,
no I am at a point that involves computations of very sparse but
relatively big multidimensional matrices. The worst case scenario is a
4-dim 2000*2000*2000*2000 float matrix. Here is what I found so far:

1. Bigarray module:
The Bigarray module fits perfectly, BUT it does not implement sparse
matrix storage. Therefore the worst case as stated above is not
feasable memorywise.

2. ocamlfloat package:
The ocamlfloat package provides a sparse matrix implmentation for
2-dimensional matrices, but I would need at least 4 dimensions.

Does anybody know a package that implements multidimensional AND
sparse matrices? In case there is no such package, would it be very
hard to write one by myself?

Thanks in advance for helping,

Andreas