[med-svn] [python-mne] 244/376: avoiding underflows in norm computation

[Yaroslav Halchenko]

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yoh pushed a commit to annotated tag v0.1
in repository python-mne.

commit 73f428e091524a194586513081017956ffd15432
Author: Alexandre Gramfort <alexandre.gramfort at inria.fr>
Date:   Thu May 12 11:11:39 2011 -0400

    avoiding underflows in norm computation
---
 mne/minimum_norm/inverse.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mne/minimum_norm/inverse.py b/mne/minimum_norm/inverse.py
index 0bdb025..2e99a5e 100755
--- a/mne/minimum_norm/inverse.py
+++ b/mne/minimum_norm/inverse.py
@@ -381,15 +381,16 @@ def prepare_inverse_operator(orig, nave, lambda2, dSPM):
     if dSPM:
         print '\tComputing noise-normalization factors...',
         noise_norm = np.zeros(inv['eigen_leads']['nrow'])
+        nrm2, = linalg.get_blas_funcs(('nrm2',), (noise_norm,))
         if inv['eigen_leads_weighted']:
             for k in range(inv['eigen_leads']['nrow']):
                 one = inv['eigen_leads']['data'][k, :] * inv['reginv']
-                noise_norm[k] = sqrt(np.sum(one ** 2))
+                noise_norm[k] = nrm2(one)
         else:
             for k in range(inv['eigen_leads']['nrow']):
                 one = sqrt(inv['source_cov']['data'][k]) * \
                             inv['eigen_leads']['data'][k, :] * inv['reginv']
-                noise_norm[k] = sqrt(np.sum(one ** 2))
+                noise_norm[k] = nrm2(one)
 
         #
         #   Compute the final result

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