message: Example uses matplotlib
diff: @@ -388,9 +388,9 @@ if(PYTHONINTERP_FOUND)
  endif(OT_FOUND)
  # Representations
  - if(SKLEARN_FOUND)
  + if(SKLEARN_FOUND AND MATPLOTLIB_FOUND)
  add_gudhi_py_test(test_representations)
  - endif(SKLEARN_FOUND)
  + endif()
  # Documentation generation is available through sphinx - requires all modules
  if(SPHINX_PATH)
  