anchor.diff:      rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
   
   # Install PETSc from source
  -ENV PETSC_VERSION 3.5.3
  +ENV PETSC_VERSION 3.6.0
   RUN cd /tmp && \
       wget -nc http://ftp.mcs.anl.gov/pub/petsc/release-snapshots/petsc-${PETSC_VERSION}.tar.gz && \
       tar -xf petsc-${PETSC_VERSION}.tar.gz && \
  
positive.code: 
  # Install sympy, petsc4py, slepc4py and swig from source
  ENV SWIG_VERSION 3.0.5
  ENV PETSC4PY_VERSION 3.5.1
  ENV SLEPC4PY_VERSION 3.5.1
  RUN pip install sympy && \
      easy_install \
       https://bitbucket.org/petsc/petsc4py/downloads/petsc4py-${PETSC4PY_VERSION}.tar.gz && \
  
negative.code:      rm -rf /tmp/*
  
  # Install SLEPc from source
  ENV SLEPC_VERSION 3.6.0
  RUN cd /tmp && \
      export PETSC_DIR=/usr/local && \
      wget -nc http://www.grycap.upv.es/slepc/download/download.php?filename=slepc-${SLEPC_VERSION}.tar.gz -O slepc-${SLEPC_VERSION}.tar.gz && \
  