From 49e96e85a1a71e110f3cf8a7e7b18a05d82597af Mon Sep 17 00:00:00 2001
From: lbaumberger <lbaumberger@student.ethz.ch>
Date: Sat, 25 Apr 2026 20:57:50 +0200
Subject: [PATCH] created two passes Pass1: compute all forces Pass2: integrate
 the forces and do the updates

If we dont separate it, we will have some inter pedestrian forces calculated on a mix of new and updated   values
---
 main.cpp | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/main.cpp b/main.cpp
index ffbc725..6e00475 100644
--- a/main.cpp
+++ b/main.cpp
@@ -58,7 +58,7 @@ int main(int argc, const char *argv[]) {
 
   // # (8 + 55N - 55 + 144 + 4 + 8 + 4 + 10)*n_p*n_iter
   for (int t = 0; t < n_iter; t++) {
-
+    // Pass1: conmpute all forces from the current state
     for (int i = 0; i < n_p; i++) {
 
       Pedestrian &p = pedestrians[i];
@@ -73,7 +73,10 @@ int main(int argc, const char *argv[]) {
 
       // # 144 flops
       compute_repulsive_effects_from_borders(board, &p);
-
+    }
+    // Pass2: integrate the forces and update the current state
+    for (int i = 0; i < n_p; i++) {
+      Pedestrian &p = pedestrians[i];
       // # 4 flops = 2 ADDs, 2 MULTs
       Vector2d w_alpha = p.curr_vel + p.f_i * dt;
 
@@ -91,18 +94,18 @@ int main(int argc, const char *argv[]) {
   std::cout << "W(n): ";
   std::cout << W;
   std::cout << " flops\n";
-  
+
   double T = stop_tsc(start);
   std::cout << "T(n): ";
   std::cout << T;
   std::cout << " cycles\n";
 
-  double P = W/T;
+  double P = W / T;
 
   std::cout << "P(n): ";
   std::cout << P;
   std::cout << " flops/cycle\n";
 
-  delete []pedestrians;
+  delete[] pedestrians;
   return 0;
 }