copy circuits

pytket/tests/predicates_test.py

@@ -1035,10 +1035,9 @@ def test_greedy_pauli_synth() -> None:
         rega[0], regb[0]
     ).SWAP(regb[1], rega[0])
     d = circ.copy()
-    pss = GreedyPauliSimp(0.5, 0.5)
-    assert not GreedyPauliSimp(0.5, 0.5, thread_timeout=0, only_reduce=False).apply(d)
-    assert pss.apply(d)
-    assert GreedyPauliSimp(0.5, 0.5, thread_timeout=10, trials=5, threads=5).apply(d)
+    assert not GreedyPauliSimp(0.5, 0.5, thread_timeout=0, only_reduce=True).apply(d)
+    assert GreedyPauliSimp(0.5, 0.5, thread_timeout=10, trials=5, threads=3).apply(d)
+
     assert np.allclose(circ.get_unitary(), d.get_unitary())
     assert d.name == "test"
     # test gateset

tket/include/tket/Transformations/GreedyPauliOptimisation.hpp

@@ -620,10 +620,10 @@ gpg_from_unordered_set(const std::vector<SymPauliTensor>& unordered_set);
  * @return Circuit
  */
 Circuit greedy_pauli_graph_synthesis_flag(
-    const Circuit& circ, std::atomic<bool>& stop_flag,
-    double discount_rate = 0.7, double depth_weight = 0.3,
-    unsigned max_lookahead = 500, unsigned max_tqe_candidates = 500,
-    unsigned seed = 0, bool allow_zzphase = false);
+    Circuit circ, std::atomic<bool>& stop_flag, double discount_rate = 0.7,
+    double depth_weight = 0.3, unsigned max_lookahead = 500,
+    unsigned max_tqe_candidates = 500, unsigned seed = 0,
+    bool allow_zzphase = false);
 
 /**
  * @brief Converts the given circuit into a GPGraph and conjugates each node

tket/src/Transformations/GreedyPauliOptimisation.cpp

@@ -749,7 +749,7 @@ Circuit greedy_pauli_set_synthesis(
 }
 
 Circuit greedy_pauli_graph_synthesis_flag(
-    const Circuit& circ, std::shared_ptr<std::atomic<bool>> stop_flag,
+    Circuit circ, std::shared_ptr<std::atomic<bool>> stop_flag,
     double discount_rate, double depth_weight, unsigned max_lookahead,
     unsigned max_tqe_candidates, unsigned seed, bool allow_zzphase) {
   if (max_lookahead == 0) {
@@ -845,6 +845,7 @@ Transform greedy_pauli_optimisation(
       if (threads_started < trials && all_threads.size() < max_threads) {
         std::shared_ptr<std::atomic<bool>> stop_flag =
             std::make_shared<std::atomic<bool>>(false);
+        // Circuit copy(circ);
         std::future<Circuit> future = std::async(
             std::launch::async,
             [&, stop_flag]() {  // Capture `stop_flag` explicitly in the lambda
@@ -855,7 +856,7 @@ Transform greedy_pauli_optimisation(
         all_threads.emplace(std::move(future), stop_flag);
         threads_started++;
         // continue to come straight back to this if statement, meaning we
-        // maximise threads
+        // maximise parallel threads
         continue;
       }
 
@@ -876,6 +877,7 @@ Transform greedy_pauli_optimisation(
 
     // Return the smallest circuit if any were found within the single
     // thread_timeout
+    // If none are found then return false
     if (circuits.empty()) return false;
     auto min = std::min_element(
         circuits.begin(), circuits.end(),