code: def dumb_sum(vecs, vals):
      N, rows, cols = vecs.shape
      res2 = np.zeros((N, rows, rows))
      for i in range(N):
          Q = vecs[i]
          L = vals[i]
          res2[i] = np.dot(Q, np.dot(np.diag(L), Q.T))
      return res2
  
file_path: dipy/dipy/reconst/tests/test_vec_val_vect.py
imports: import numpy
  from numpy.random import randn
  from numpy.testing import assert_almost_equal
  from dipy.reconst.vec_val_sum import vec_val_vect
label_desc: Use image node_id 3 for calling a global function with example usage: dumb_sum(vecs, vals) and returns: res2