diff --git a/doc/conf.py b/doc/conf.py
index 54135023..6a6eedfe 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -126,7 +126,7 @@ for mod_name in MOCK_MODULES:
 # If your extensions are in another directory, add it here. If the directory
 # is relative to the documentation root, use os.path.abspath to make it
 # absolute, like shown here.
-#sys.path.append(os.path.abspath('.'))
+sys.path.append(os.path.abspath('sphinxext'))
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
@@ -140,7 +140,15 @@ for mod_name in MOCK_MODULES:
 
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
-extensions = ['sphinx.ext.autodoc', 'sphinx.ext.viewcode']
+extensions = ['sphinx.ext.autodoc', 'sphinx.ext.viewcode',
+              'matplotlib.sphinxext.mathmpl',
+              'matplotlib.sphinxext.only_directives',
+              'matplotlib.sphinxext.plot_directive',
+              'matplotlib.sphinxext.ipython_directive',
+              'sphinx.ext.doctest',
+              'ipython_console_highlighting',
+              'inheritance_diagram',
+              'numpydoc'] 
 
 # ----------------------- READTHEDOCS ------------------
 on_rtd = os.environ.get('READTHEDOCS', None) == 'True'
diff --git a/doc/tuto_GP_regression.rst b/doc/tuto_GP_regression.rst
index 7d1a43df..a713eb4c 100644
--- a/doc/tuto_GP_regression.rst
+++ b/doc/tuto_GP_regression.rst
@@ -146,3 +146,13 @@ The flag ``ARD=True`` in the definition of the Matern kernel specifies that we w
     :height: 350px
 
     Contour plot of the best predictor (posterior mean).
+
+.. plot::
+
+   import matplotlib.pyplot as plt
+   import numpy as np
+   x = np.random.randn(1000)
+   plt.hist( x, 20)
+   plt.grid()
+   plt.title(r'Normal: $\mu=%.2f, \sigma=%.2f$'%(x.mean(), x.std()))
+   plt.show()