DOC: Point out that inverse modeling needs an average reference proje…

…ctor ready to not raise an error (#12420)

Co-authored-by: Daniel McCloy <dan@mccloy.info>
Co-authored-by: Eric Larson <larson.eric.d@gmail.com>

doc/changes/devel/12420.other.rst

@@ -0,0 +1 @@
+Clarify in the :ref:`EEG referencing tutorial <tut-set-eeg-ref>` that an average reference projector ready is required for inverse modeling, by :newcontrib:`Nabil Alibou`

doc/changes/names.inc

@@ -390,6 +390,8 @@
 
 .. _Motofumi Fushimi: https://github.com/motofumi-fushimi/motofumi-fushimi.github.io
 
+.. _Nabil Alibou: https://github.com/nabilalibou
+
 .. _Natalie Klein: https://github.com/natalieklein
 
 .. _Nathalie Gayraud: https://github.com/ngayraud

tutorials/preprocessing/55_setting_eeg_reference.py

@@ -131,7 +131,7 @@
 # :meth:`~mne.io.Raw.set_eeg_reference` with ``ref_channels='average'``. Just
 # as above, this will not affect any channels marked as "bad", nor will it
 # include bad channels when computing the average. However, it does modify the
-# :class:`~mne.io.Raw` object in-place, so we'll make a copy first so we can
+# :class:`~mne.io.Raw` object in-place, so we'll make a copy first, so we can
 # still go back to the unmodified :class:`~mne.io.Raw` object later:
 
 # sphinx_gallery_thumbnail_number = 4
@@ -241,9 +241,13 @@
 # the source modeling is performed. In contrast, applying an average reference
 # by the traditional subtraction method offers no such guarantee.
 #
-# For these reasons, when performing inverse imaging, *MNE-Python will raise
-# a ``ValueError`` if there are EEG channels present and something other than
-# an average reference strategy has been specified*.
+# .. important:: For these reasons, when performing inverse imaging, MNE-Python
+#                will raise a ``ValueError`` if there are EEG channels present
+#                and something other than an average reference projector strategy
+#                has been specified. To ensure correct functioning consider
+#                calling :meth:`set_eeg_reference(projection=True)
+#                <mne.io.Raw.set_eeg_reference>` to add an average
+#                reference as a projector.
 #
 # .. LINKS
 #