DDM iteration spectrum

git-svn-id: https://geuz.org/svn/gmsh/trunk@19851 59c8cabf-10d6-4a28-b43f-3936b85956c4
Oops


git-svn-id: https://geuz.org/svn/gmsh/trunk@19852 59c8cabf-10d6-4a28-b43f-3936b85956c4