优化仿真求解性能并修复流量闭合问题（初版）

app/simulation/solvers/solver.py

@@ -807,9 +807,13 @@ def _integrate_scipy_stepwise(
                 segment_accepted_steps += 1
                 step_end_time = float(solver.t)
                 step_end_state = [float(value) for value in solver.y]
+                crosses_sample = (
+                    sample_index < len(sample_times)
+                    and sample_times[sample_index] <= step_end_time
+                )
                 dense_output = (
                     solver.dense_output()
-                    if sample_times or state_transition_handler is not None
+                    if crosses_sample or state_transition_handler is not None
                     else None
                 )
 
@@ -918,11 +922,11 @@ def _integrate_scipy_stepwise(
                     else last_accepted_time
                 )
                 if sample_times:
-                    assert dense_output is not None
                     while (
                         sample_index < len(sample_times)
                         and sample_times[sample_index] <= last_accepted_time
                     ):
+                        assert dense_output is not None
                         sample_time = float(sample_times[sample_index])
                         sample_state = [
                             float(value) for value in dense_output(sample_time)