For now just runnint the CIs.

Codecov Report

Merging #6636 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master   #6636      +/-   ##
=========================================
+ Coverage   89.38%   89.4%   +0.02%     
=========================================
  Files         416     416              
  Lines       75127   75130       +3     
  Branches    12352   12352              
=========================================
+ Hits        67150   67172      +22     
+ Misses       5141    5126      -15     
+ Partials     2836    2832       -4

I thought I would also win something in terms of speed with the vectorization but that's not the case. test_make_inverse_operator_vector takes the same time with both implementations.

Travis errors are unrelated:

>               raise URLError(err)
3391E               urllib.error.URLError: <urlopen error timed out>

Great refactor! Looks much cleaner. Since you touched the rotation logic, did you double check that the vectors in the VectorSourceEstimate are rotated correctly?

@wmvanvliet yes. If you check the first commit bd2b703, I ran both computations, put assert and run the entire test suite. All green lights!

            xx = np.matmul(
                np.transpose(source_nn.reshape(n_vertices, 3, 3),
                             axes=[0, 2, 1]),
                data.reshape(n_vertices, 3, -1)
            )
            np.testing.assert_allclose(xx, data_rot)