From 9409f0ff8f550133b608a9375da142456e7ccab4 Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Thu, 7 Nov 2019 10:47:54 -0600
Subject: [PATCH] Fix delayed group indexing errors

---
 src/mgxs.cpp                  | 20 +++++++-------------
 src/tallies/tally_scoring.cpp | 14 +++++++-------
 2 files changed, 14 insertions(+), 20 deletions(-)

diff --git a/src/mgxs.cpp b/src/mgxs.cpp
index 1fca663080..05ce05ac0b 100644
--- a/src/mgxs.cpp
+++ b/src/mgxs.cpp
@@ -548,8 +548,7 @@ Mgxs::sample_fission_energy(int gin, int& dg, int& gout)
   double nu_fission = xs_t->nu_fission(cache[tid].a, gin);
 
   // Find the probability of having a prompt neutron
-  double prob_prompt =
-       xs_t->prompt_nu_fission(cache[tid].a, gin);
+  double prob_prompt = xs_t->prompt_nu_fission(cache[tid].a, gin);
 
   // sample random numbers
   double xi_pd = prn() * nu_fission;
@@ -564,8 +563,7 @@ Mgxs::sample_fission_energy(int gin, int& dg, int& gout)
 
     // sample the outgoing energy group
     gout = 0;
-    double prob_gout =
-         xs_t->chi_prompt(cache[tid].a, gin, gout);
+    double prob_gout = xs_t->chi_prompt(cache[tid].a, gin, gout);
     while (prob_gout < xi_gout) {
       gout++;
       prob_gout += xs_t->chi_prompt(cache[tid].a, gin, gout);
@@ -575,11 +573,9 @@ Mgxs::sample_fission_energy(int gin, int& dg, int& gout)
     // the neutron is delayed
 
     // get the delayed group
-    dg = 0;
-    while (xi_pd >= prob_prompt) {
-      dg++;
-      prob_prompt +=
-           xs_t->delayed_nu_fission(cache[tid].a, dg, gin);
+    for (dg = 0; dg < num_delayed_groups; ++dg) {
+      prob_prompt += xs_t->delayed_nu_fission(cache[tid].a, dg, gin);
+      if (xi_pd < prob_prompt) break;
     }
 
     // adjust dg in case of round-off error
@@ -587,12 +583,10 @@ Mgxs::sample_fission_energy(int gin, int& dg, int& gout)
 
     // sample the outgoing energy group
     gout = 0;
-    double prob_gout =
-         xs_t->chi_delayed(cache[tid].a, dg, gin, gout);
+    double prob_gout = xs_t->chi_delayed(cache[tid].a, dg, gin, gout);
     while (prob_gout < xi_gout) {
       gout++;
-      prob_gout +=
-           xs_t->chi_delayed(cache[tid].a, dg, gin, gout);
+      prob_gout += xs_t->chi_delayed(cache[tid].a, dg, gin, gout);
     }
   }
 }
diff --git a/src/tallies/tally_scoring.cpp b/src/tallies/tally_scoring.cpp
index 37310070fe..7ef05837c9 100644
--- a/src/tallies/tally_scoring.cpp
+++ b/src/tallies/tally_scoring.cpp
@@ -1720,7 +1720,7 @@ score_general_mg(const Particle* p, int i_tally, int start_index,
                 model::tally_filters[i_dg_filt].get())};
               // Tally each delayed group bin individually
               for (auto d_bin = 0; d_bin < filt.n_bins(); ++d_bin) {
-                auto d = filt.groups()[d_bin];
+                auto d = filt.groups()[d_bin] - 1;
                 score = p->wgt_absorb_ * flux;
                 if (i_nuclide >= 0) {
                   score *=
@@ -1802,7 +1802,7 @@ score_general_mg(const Particle* p, int i_tally, int start_index,
             model::tally_filters[i_dg_filt].get())};
           // Tally each delayed group bin individually
           for (auto d_bin = 0; d_bin < filt.n_bins(); ++d_bin) {
-            auto d = filt.groups()[d_bin];
+            auto d = filt.groups()[d_bin] - 1;
             if (i_nuclide >= 0) {
               score = flux * atom_density
                 * get_nuclide_xs(i_nuclide, MG_GET_XS_DELAYED_NU_FISSION,
@@ -1842,7 +1842,7 @@ score_general_mg(const Particle* p, int i_tally, int start_index,
                 model::tally_filters[i_dg_filt].get())};
               // Tally each delayed group bin individually
               for (auto d_bin = 0; d_bin < filt.n_bins(); ++d_bin) {
-                auto d = filt.groups()[d_bin];
+                auto d = filt.groups()[d_bin] - 1;
                 score = p->wgt_absorb_ * flux;
                 if (i_nuclide >= 0) {
                   score *=
@@ -1902,8 +1902,8 @@ score_general_mg(const Particle* p, int i_tally, int start_index,
           for (auto i = 0; i < p->n_bank_; ++i) {
             auto i_bank = simulation::fission_bank.size() - p->n_bank_ + i;
             const auto& bank = simulation::fission_bank[i_bank];
-            auto g = bank.delayed_group;
-            if (g != 0) {
+            auto g = bank.delayed_group - 1;
+            if (g != -1) {
               if (i_nuclide >= 0) {
                 score += simulation::keff * atom_density * bank.wgt * flux
                   * get_nuclide_xs(i_nuclide, MG_GET_XS_DECAY_RATE, p_g,
@@ -1923,7 +1923,7 @@ score_general_mg(const Particle* p, int i_tally, int start_index,
                 // Find the corresponding filter bin and then score
                 for (auto d_bin = 0; d_bin < filt.n_bins(); ++d_bin) {
                   auto d = filt.groups()[d_bin];
-                  if (d == g)
+                  if (d == g + 1)
                     score_fission_delayed_dg(i_tally, d_bin, score,
                       score_index);
                 }
@@ -1941,7 +1941,7 @@ score_general_mg(const Particle* p, int i_tally, int start_index,
             model::tally_filters[i_dg_filt].get())};
           // Tally each delayed group bin individually
           for (auto d_bin = 0; d_bin < filt.n_bins(); ++d_bin) {
-            auto d = filt.groups()[d_bin];
+            auto d = filt.groups()[d_bin] - 1;
             if (i_nuclide >= 0) {
               score += atom_density * flux
                 * get_nuclide_xs(i_nuclide, MG_GET_XS_DECAY_RATE,