get rid of pointless division by zero warning

bfps/DNS.py

@@ -389,8 +389,8 @@ class DNS(_code):
                 self.statistics['kMeta' + suffix] *= 0.8
         self.statistics['Lint'] = ((np.pi /
                                     (2*self.statistics['Uint']**2)) *
-                                   np.nansum(self.statistics['energy(k)'] /
-                                                self.statistics['kshell']))
+                                   np.sum(self.statistics['energy(k)'][1:-2] /
+                                          self.statistics['kshell'][1:-2]))
         self.statistics['Re'] = (self.statistics['Uint'] *
                                  self.statistics['Lint'] /
                                  self.parameters['nu'])