rewrite example

git-svn-id: svn://scm.gforge.inria.fr/svnroot/sofa/trunk@9998 b7f1a160-662a-0410-a6d8-bea165342f16
Fix compilation with SOFA_DOUBLE

git-svn-id: svn://scm.gforge.inria.fr/svnroot/sofa/trunk@9999 b7f1a160-662a-0410-a6d8-bea165342f16