Incorporating changes requested by @giudgiud

openmc/mgxs/mgxs.py

@@ -2872,7 +2872,7 @@ class DiffusionCoefficient(TransportXS):
        \phi \rangle}{\langle \phi \rangle} \\
        D = \frac{1}{3 \sigma_{tr}}
        \end{aligned}
-       
+
     To incorporate the effect of scattering multiplication in the above
     relation, the `nu` parameter can be set to `True`.
 
@@ -3057,7 +3057,7 @@ class DiffusionCoefficient(TransportXS):
                     filter_bins=[('P1',)],
                     squeeze=True)
             p1_tally._scores = ['scatter-1']
-            
+
             total = self.tallies['total'] / self.tallies['flux (tracklength)']
             trans_corr = p1_tally / self.tallies['flux (analog)']
             transport = (total - trans_corr)
@@ -3066,7 +3066,7 @@ class DiffusionCoefficient(TransportXS):
 
         else:
             dif_coef = self.rxn_rate_tally
-            
+
         flux_tally = condensed_xs.tallies['flux (tracklength)']
         condensed_xs._tallies = OrderedDict()
         condensed_xs._tallies[self._rxn_type] = dif_coef
@@ -5633,8 +5633,8 @@ class Chi(MGXS):
     """
 
     # Store whether or not the number density should be removed for microscopic
-    # values of this data; since this chi data is normalized to 1.0, the 
-    # data should not be divided by the number density 
+    # values of this data; since this chi data is normalized to 1.0, the
+    # data should not be divided by the number density
     _divide_by_density = False
 
     def __init__(self, domain=None, domain_type=None, groups=None,
@@ -6554,7 +6554,7 @@ class MeshSurfaceMGXS(MGXS):
         surfaces = df.pop(col_key)
         df.insert(len(self.domain.dimension), col_key, surfaces)
         if len(self.domain.dimension) == 1:
-            df.sort_values(by=[(mesh_str, 'x'), (mesh_str, 'surf')] 
+            df.sort_values(by=[(mesh_str, 'x'), (mesh_str, 'surf')]
                     + columns, inplace=True)
         elif len(self.domain.dimension) == 2:
             df.sort_values(by=[(mesh_str, 'x'), (mesh_str, 'y'),
@@ -6642,7 +6642,7 @@ class Current(MeshSurfaceMGXS):
         is None unless the multi-group cross section has been computed.
     num_subdomains : int
         The number of subdomains is equal to the number of mesh surfaces times
-        two to account for both the incoming and outgoing current from the 
+        two to account for both the incoming and outgoing current from the
         mesh cell surfaces.
     num_nuclides : int
         Unused in MeshSurfaceMGXS

src/mgxs.cpp

@@ -382,7 +382,7 @@ Mgxs::Mgxs(const std::string& in_name, const std::vector<double>& mat_kTs,
     // We will do this by treating the multiple temperatures of a nuclide as
     // a different nuclide. Mathematically this just means the temperature
     // interpolant is included in the number density.
-    // These interpolants are contained within interp.
+    // These interpolants are contained within interpolant.
     std::vector<double> interpolant;     // the interpolant for the Mgxs
     std::vector<int> temp_indices;       // the temperature index for each Mgxs
     std::vector<Mgxs*> mgxs_to_combine;  // The Mgxs to combine

src/scattdata.cpp

@@ -38,12 +38,21 @@ ScattData::base_init(int order, const xt::xtensor<int, 1>& in_gmin,
     mult[gin] = in_mult[gin];
 
     // Make sure the multiplicity does not have 0s
+    unsigned long int num_converted = 0;
     for (int go = 0; go < mult[gin].size(); go++) {
       if (mult[gin][go] == 0.) {
+        num_converted += 1;
         mult[gin][go] = 1.;
       }
     }
 
+    if (num_converted > 0) {
+      // Raise a warning to the user if we did have to do the conversion
+      std::string msg = std::to_string(num_converted) +
+           "entries in the Multiplicity Matrix were changed from 0 to 1";
+      warning(msg);
+    }
+
     // Make sure the energy is normalized
     double norm = std::accumulate(energy[gin].begin(), energy[gin].end(), 0.);