Merge pull request mne-tools#3007 from Eric89GXL/fix-timing

FIX: More tolerant

mne/preprocessing/maxwell.py

@@ -686,7 +686,9 @@ def _check_pos(pos, head_frame, raw, st_fixed, sfreq):
     t_off = raw.first_samp / raw.info['sfreq']
     if not np.array_equal(t, np.unique(t)):
         raise ValueError('Time points must unique and in ascending order')
-    if not _time_mask(t, tmin=t_off, tmax=None, sfreq=sfreq).all():
+    # We need an extra 1e-3 (1 ms) here because MaxFilter outputs values
+    # only out to 3 decimal places
+    if not _time_mask(t, tmin=t_off - 1e-3, tmax=None, sfreq=sfreq).all():
         raise ValueError('Head position time points must be greater than '
                          'first sample offset, but found %0.4f < %0.4f'
                          % (t[0], t_off))

mne/preprocessing/tests/test_maxwell.py

@@ -172,10 +172,10 @@ def test_movement_compensation():
     head_pos_bad[0, 0] = raw.first_samp / raw.info['sfreq'] - 1e-2
     assert_raises(ValueError, maxwell_filter, raw, head_pos=head_pos_bad)
     # make sure numerical error doesn't screw it up, though
-    head_pos_bad[0, 0] = raw.first_samp / raw.info['sfreq'] - 1e-4
+    head_pos_bad[0, 0] = raw.first_samp / raw.info['sfreq'] - 5e-4
     raw_sss_tweak = maxwell_filter(raw, head_pos=head_pos_bad,
                                    origin=mf_head_origin)
-    assert_meg_snr(raw_sss_tweak, raw_sss, 2., 10.)
+    assert_meg_snr(raw_sss_tweak, raw_sss, 2., 10., chpi_med_tol=11)
 
 
 @slow_test