From d483b99e47cafb5e756932fc4a26e9b3575fbddb Mon Sep 17 00:00:00 2001
From: Peter Reinholdt <peter.reinholdt@gmail.com>
Date: Mon, 18 Aug 2025 12:29:29 +0200
Subject: [PATCH 1/2] Fix integer division in end_chunk_idx

---
 pyci/src/common.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pyci/src/common.cpp b/pyci/src/common.cpp
index b6657be1..675b58a3 100644
--- a/pyci/src/common.cpp
+++ b/pyci/src/common.cpp
@@ -30,7 +30,7 @@ long get_num_threads(void) {
 }
 
 long end_chunk_idx(const long thread_idx, const long num_threads, const long sideLength) {
-    return ceil(sqrt(thread_idx / num_threads) * sideLength);
+    return ceil(static_cast<double>(thread_idx) / static_cast<double>(num_threads) * sideLength);
 }
 
 void set_num_threads(const long n) {

From 8bff23beb3867fef0e77108f513fd40f73bff308 Mon Sep 17 00:00:00 2001
From: Peter Reinholdt <peter.reinholdt@gmail.com>
Date: Mon, 18 Aug 2025 12:32:54 +0200
Subject: [PATCH 2/2] Fix data race

---
 pyci/src/hci.cpp | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/pyci/src/hci.cpp b/pyci/src/hci.cpp
index e934c845..10ff9d7c 100644
--- a/pyci/src/hci.cpp
+++ b/pyci/src/hci.cpp
@@ -267,11 +267,9 @@ long add_hci(const SQuantOp &ham, WfnType &wfn, const double *coeffs, const doub
         v_threads.emplace_back(&hci_thread<WfnType>, std::ref(ham), std::ref(wfn),
                                std::ref(v_wfns.back()), coeffs, eps, start, end);
     }
-    long n = 0;
-    for (auto &thread : v_threads) {
-        thread.join();
-        wfn.add_dets_from_wfn(v_wfns[n++]);
-    }
+    for (auto &thread : v_threads) thread.join();
+    for (auto &wf : v_wfns) wfn.add_dets_from_wfn(wf);
+
     return wfn.ndet - ndet_old;
 }