Hi, Along the lines of python's numarray [1], we need some way of operating pointwise (and inner/outer operations) on Mat/Vec objects. In particular, we need things like the following: (a) v=add.reduce(m) (sum along rows/cols of a Mat to produce a Vec) (b) m=add.outer(v1,v2) (sum of all elements of two Vecs to produce a Mat) (c) m=add(m1,m2) (pointwise sum) (d) m=exp(m) (pointwise exp) Right now we can do (a) and (b) using dgemm and single column/row matrices with just 1s, and we can do (c) using SetValues. But for (d): it looks like we will be writing a c-loop ? And I don't think the PETSc interface to dgemm (MatMatMult*) is general enough to do (b) (we need one of the products to be added to the other product, so beta=1). It would be easy enough to use numarray to "shadow" the PETSc arrays (using *GetArray) and then make numarray do the work, but this seems doomed to failure because numarray is inherently dense. Simon. [1]: http://stsdas.stsci.edu/numarray/numarray-1.3.html/node35.html -- Simon Burton, B.Sc. Licensed PO Box 8066 ANU Canberra 2601 Australia Ph. 61 02 6249 6940 http://arrowtheory.com