119 lines
3.3 KiB
C++
119 lines
3.3 KiB
C++
#include "mylib.h"
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#include "algorithm" // GH: transform()
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#include <cassert> // assert()
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#include <cmath>
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#include <iostream>
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#include <functional> // multiplies<>{}
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#include <list>
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#include <numeric> // iota()
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#ifdef _OPENMP
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#include <omp.h>
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#endif
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#include <vector>
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using namespace std;
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double scalar(vector<double> const &x, vector<double> const &y)
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{
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assert(x.size() == y.size()); // switch off via compile flag: -DNDEBUG
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size_t const N = x.size();
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double sum = 0.0;
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#pragma omp parallel for default(none) shared(x,y,N) reduction(+:sum)
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for (size_t i = 0; i < N; ++i)
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{
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sum += x[i] * y[i];
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//sum += exp(x[i])*log(y[i]);
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}
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return sum;
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}
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double scalar_trans(vector<double> const &x, vector<double> const &y)
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{
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assert(x.size() == y.size()); // switch off via compile flag: -DNDEBUG
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vector<double> z(x.size());
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transform(cbegin(x),cend(x),cbegin(y),begin(z),std::multiplies<>{});
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double sum = 0.0;
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#pragma omp parallel for default(none) shared(z) reduction(+:sum)
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for (auto pi = cbegin(z); pi!=cend(z); ++pi)
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{
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sum += *pi;
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}
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return sum;
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}
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double norm(vector<double> const &x)
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{
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size_t const N = x.size();
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double sum = 0.0;
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#pragma omp parallel for default(none) shared(x,N) reduction(+:sum)
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for (size_t i = 0; i < N; ++i)
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{
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sum += x[i]*x[i];
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}
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return sum;
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}
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// ------------------------------------------------------------------
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double scalar_manual(vector<double> const &x, vector<double> const &y)
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{
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assert(x.size() == y.size());
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size_t const N = x.size();
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double sum = 0.0;
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#pragma omp parallel default(none) shared(x,y,N) reduction(+:sum)
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{
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int tid = omp_get_thread_num();
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int nth = omp_get_num_threads();
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// manual cyclic distribution
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for (size_t i = static_cast<size_t>(tid); i < N; i += static_cast<size_t>(nth)) {
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sum += x[i] * y[i];
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}
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}
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return sum;
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}
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// ------------------------------------------------------------------
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vector<int> reduction_vec(int n)
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{
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vector<int> vec(n);
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#pragma omp parallel default(none) shared(cout) reduction(VecAdd:vec)
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{
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#pragma omp barrier
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#pragma omp critical
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cout << omp_get_thread_num() << " : " << vec.size() << endl;
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#pragma omp barrier
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iota( vec.begin(),vec.end(), omp_get_thread_num() );
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#pragma omp barrier
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}
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return vec;
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}
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// ------------------------------------------------------------------
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vector<int> reduction_vec_append(int n)
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{
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// determine number of threads that will be used
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int nth = 1;
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#pragma omp parallel
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{
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#pragma omp master
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nth = omp_get_num_threads();
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}
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vector<int> result;
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result.resize(static_cast<size_t>(n) * static_cast<size_t>(nth));
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// Each thread will fill its own contiguous block [tid*n, tid*n + n)
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#pragma omp parallel default(none) shared(result,n)
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{
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int tid = omp_get_thread_num();
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// create local vector and initialize with a pattern (e.g., tid + k)
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vector<int> local(n);
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iota(local.begin(), local.end(), tid); // local[k] = tid + k
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size_t offset = static_cast<size_t>(tid) * static_cast<size_t>(n);
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for (int k = 0; k < n; ++k) {
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result[offset + static_cast<size_t>(k)] = local[static_cast<size_t>(k)];
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}
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}
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return result;
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}
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