OP2/PyOP2 — pull request #401 by wence- (2014-09-19 15:25:59+00:00)
Title: Mat zeros

Fill newly created matrices with zeros, so petsc doesn't compact the space.

Additionally, rework sparsity construction to remove code duplication and implement parallel sparsity construction for all extruded cases.

AFAICT, this doesn't change the speed of sparsity building.