Building an arpack extension turned out to be surprisingly simple. For example for dsaupd: f2py -c dsaupd.f -m dsaupd -L/usr/lib/blas/atlas:/usr/lib/lapack/atlas -llapack -lblas -larpack It took me a long time to get the command down to something that simple. Took me a while even to figure out I could just use the arpack library on my computer rather than re-linking all of arpack! I was able to import the dsaupd.so python module just fine and I was also able to call it just fine. I'll have to tweak the pyf file in order to get some proper output. But this gives me confidence that arpack is easy to hook into which is what others have said in the past, but without any experience with f2py I had no idea myself. f2py is awesome, for anyone who doesn't know. Matlab has interfaces for the arpack functions like dsaupd, dseupd, dnaupd, znaupd, zneupd (the mex file documentation claims those are the only ones, but they have more). Matlab has a C interface to these functions in arpackc.mex* and the script eigs.m does the grunt work, providing a very high-level interface as well as doing some linear algebra (the same type of stuff that is done in arpack's examples directory I gather) and various other things. My idea is (if I have time) to write an eigs-like function in python that will only perform a subset of what Matlab's eigs does for. It will, for example, compute a certain number of eigenvalues and eigenvectors for a real, sparse, symmetric matrix (the case I'm interested in)... I hope that this subset-of-matlab's-eigs function will not be too hard to write. Then more functionality can be added on to eigs.py later... Does this make sense? Has anyone else started work on arpack integration at all? -- David Grant http://www.davidgrant.ca