From 1c8ee8ae254bbdfa8be62be8d5d2aae14808ec3e Mon Sep 17 00:00:00 2001
From: "lisa.pizzo" <lisa.pizzo@noreply.imsc.uni-graz.at>
Date: Thu, 4 Dec 2025 12:07:13 +0100
Subject: [PATCH] Main file - Exercise 5

---
 Sheet5/mainEx5.cpp | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 Sheet5/mainEx5.cpp

diff --git a/Sheet5/mainEx5.cpp b/Sheet5/mainEx5.cpp
new file mode 100644
index 0000000..d713e88
--- /dev/null
+++ b/Sheet5/mainEx5.cpp
@@ -0,0 +1,45 @@
+// HOW TO COMPILE ON MACOS
+// export CPPFLAGS="-I/opt/homebrew/opt/libomp/include"
+// export LDFLAGS="-L/opt/homebrew/opt/libomp/lib"
+// clang++ -std=c++17 -O3 -Xpreprocessor -fopenmp $CPPFLAGS main.cpp bench_funcs.cpp $LDFLAGS -lomp -o Ex5
+// ./Ex5
+
+#include <iostream>
+#include <vector>
+#include <chrono>
+#include <omp.h>
+#include "bench_funcs.h"
+
+using namespace std;
+using namespace std::chrono;
+
+int main() {
+    size_t n = 200000;       // FEM system size
+    size_t maxit = 5000;
+    double omega = 1.0;
+    double tol = 1e-8;
+
+    // show threads
+    #pragma omp parallel
+    {
+        #pragma omp single
+        cout << "Using " << omp_get_num_threads() << " OpenMP threads\n";
+    }
+
+    CSR K;
+    vector<double> f, u;
+
+    cout << "\nBuilding FEM system (parallel)\n";
+    auto t0 = high_resolution_clock::now();
+    build_fem_system(n, K, f);
+    auto t1 = high_resolution_clock::now();
+    cout << "Assembly time = " << duration<double>(t1 - t0).count() << " s\n";
+
+    cout << "\nRunning Jacobi solver (parallel)\n";
+    t0 = high_resolution_clock::now();
+    jacobi_csr_parallel(K, f, u, maxit, omega, tol);
+    t1 = high_resolution_clock::now();
+
+    cout << "Jacobi time = " << duration<double>(t1 - t0).count() << " s\n";
+    cout << "Done\n";
+}