PISM version 0.7.1 and PETSc 3.6.1

PISM v0.7.1 was released 30 June 2015. In addition to bug fixes this version adds support for PETSc 3.6.1, which was released 22 July 2015.

PETSc 3.6.0 is not supported due to a bug in PETSc. Please use PETSc 3.5.4 or >= 3.6.1 with PISM.