sheet 5 not tested

sheet5/1/mylib.cpp

@@ -0,0 +1,136 @@
+#include "mylib.h"
+#include <cassert>       // assert()
+#include <cmath>
+#include <iostream>
+#include <functional>    // multiplies<>{}
+#include <list>
+#include <numeric>       // iota()
+#ifdef _OPENMP
+#include <omp.h>
+#endif
+#include <vector>
+using namespace std;
+
+double scalar(vector<double> const &x, vector<double> const &y)
+{
+    assert(x.size() == y.size()); // switch off via compile flag: -DNDEBUG
+    size_t const N = x.size();
+    double sum = 0.0;
+    if (!omp_in_parallel())
+    {
+        // Safe to start a parallel region
+        #pragma omp parallel for default(none) shared(x,y,N) reduction(+:sum) schedule(runtime)
+        for (size_t i = 0; i < N; ++i)
+            sum += x[i] * y[i];
+    }
+    else
+    {
+        // Already inside parallel region: do it sequentially to avoid nested parallelism
+        for (size_t i = 0; i < N; ++i)
+            sum += x[i] * y[i];
+    }
+    return sum;
+}
+
+
+double scalar_parrallel_env(vector<double> const &x, vector<double> const &y)
+{
+    assert(x.size() == y.size()); // switch off via compile flag: -DNDEBUG
+    size_t const N = x.size();
+    double sum = 0.0;
+    
+    
+    // Safe to start a parallel region
+    #pragma omp parallel  default(none) shared(x,y,N,cout) reduction(+:sum)
+    {
+        int tid = omp_get_thread_num();
+        int threadCount = omp_get_num_threads();
+        cout << threadCount << endl;
+
+        
+
+
+        for (size_t i = tid*N/threadCount; i < tid*(N + 1)/threadCount; ++i)
+        {
+            sum += x[i] * y[i];
+        }
+    }
+    
+    return sum;
+}
+
+double norm(vector<double> const &x)
+{
+    size_t const N = x.size();
+    double sum = 0.0;
+#pragma omp parallel for default(none) shared(x,N) reduction(+:sum)
+    for (size_t i = 0; i < N; ++i)
+    {
+        sum += x[i]*x[i];
+    }
+    return sum;
+}
+
+
+
+vector<int> reduction_vec(int n)
+{ 
+    vector<int> vec(n);
+#pragma omp parallel default(none) shared(cout) reduction(VecAdd:vec)
+    {
+        #pragma omp barrier
+        #pragma omp critical
+        cout << omp_get_thread_num() << " : " << vec.size() << endl;
+        #pragma omp barrier
+        iota( vec.begin(),vec.end(), omp_get_thread_num() );
+        #pragma omp barrier
+
+    }
+    return vec;
+}
+
+vector<int> reduction_vec_append(int n)
+{
+    vector<int> vec(n);
+    #pragma omp parallel default(none) shared(cout,n) reduction(VecAppend:vec)
+    {
+        int tid = omp_get_thread_num();
+
+        vector<int> local(n);
+        iota(local.begin(), local.end(), tid);
+
+        #pragma omp critical
+        cout << tid << " : " << local.size() << endl;
+
+        vec = local;  
+    }
+
+    return vec;
+}
+
+
+
+double scalar_trans(vector<double> const &x, vector<double> const &y)
+{
+    assert(x.size() == y.size()); // switch off via compile flag: -DNDEBUG
+    vector<double> z(x.size());
+    //list<double> z(x.size());  // parallel for-loop on iterators not possible (missing 'operator-')
+                                 // c++-20 CLANG_, ONEAPI_:condition of OpenMP for loop must be a relational comparison 
+    
+    transform(cbegin(x),cend(x),cbegin(y),begin(z),std::multiplies<>{});
+    
+    double sum = 0.0;
+#pragma omp parallel for default(none) shared(z) reduction(+:sum)
+    for (auto pi = cbegin(z); pi!=cend(z); ++pi)
+    {
+        sum += *pi;
+    }
+    //for (auto val: z)
+    //{
+        //sum += val;
+    //}    
+    return sum;
+}
+
+
+