[gambit-list] Number crunching

Christian Jaeger christian at pflanze.mine.nu
Thu Apr 19 14:09:55 EDT 2007


Huang Jianshi wrote:
> Hi,
>
> I'm new to Gambit. I read the benchmark and Gambit performs on the  
> top of the list. I want to ask if there is any tutorial/manual/ 
> examples on showing how to write efficient code on number crunching  
> task, especially matrix operations and floating point operations.
>   

Brad Lucier is the main number crunching specialist here. He has some
code for matrix operations on his web page (though I don't know how
current).

If you want fast handling of single floats (as opposed to vectors or
matrices), garbage collection is an issue since floats are normally
boxed; you can get around this by using (declare (flonum) (not safe)) in
the relevant sections, and/or ##flonum.{*,+,-,/,..} operators. (Floats
are still boxed across real function calls, though.)

If you have sparse matrices or want to transparently use multiple cpu's
or a cluster without decomposing the work into smaller tasks yourself,
the PETSc library may be for you. I did start implementing bindings some
time ago but have suspendet that work for now. (I did also plan an
infrastructure and did some coding experiments for working with big time
series (in disk files) efficiently, but that project has then been
cancelled by the customer.)

Christian.




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