sheet 5

Sheet_5/bsp_5_1/mylib.h

@@ -0,0 +1,93 @@
+#pragma once
+#include <cassert>
+#include <iomanip>             // setw()
+#include <iostream>
+#include <omp.h>
+#include <vector>
+
+/** 	Inner product
+	@param[in] x	vector
+	@param[in] y	vector
+	@return 	    resulting Euclidian inner product <x,y>
+*/
+double scalar(std::vector<double> const &x, std::vector<double> const &y);
+double scalar_manual(std::vector<double> const &x, std::vector<double> const &y);
+double scalar_trans(std::vector<double> const &x, std::vector<double> const &y);
+
+
+/** 	l2-norm
+	@param[in] x	vector
+	@return 	    resulting Euclidian norm
+*/
+double norm(std::vector<double> const &x);
+
+/** 	 Vector @p b adds its elements to vector @p a .
+	@param[in] a	vector
+	@param[in] b	vector
+	@return 	     a+=b componentwise
+*/
+template<class T>
+std::vector<T> &operator+=(std::vector<T> &a, std::vector<T> const &b)
+{
+    assert(a.size()==b.size());
+    for (size_t k = 0; k < a.size(); ++k) {
+        a[k] += b[k];
+    }
+    return a;
+}
+
+// Declare the reduction operation in OpenMP for an STL-vector
+//   omp_out += omp_in  requires operator+=(vector<int> &, vector<int> const &) from above
+// ------------------------------------------------------------
+// https://scc.ustc.edu.cn/zlsc/tc4600/intel/2016.0.109/compiler_c/common/core/GUID-7312910C-D175-4544-99C5-29C12D980744.htm
+// https://gist.github.com/eruffaldi/7180bdec4c8c9a11f019dd0ba9a2d68c
+// https://stackoverflow.com/questions/29633531/user-defined-reduction-on-vector-of-varying-size
+//  see also p.74ff in  https://www.fz-juelich.de/ias/jsc/EN/AboutUs/Staff/Hagemeier_A/docs-parallel-programming/OpenMP-Slides.pdf
+#pragma omp declare reduction(VecAdd : std::vector<int>  : omp_out += omp_in) \
+ initializer (omp_priv=omp_orig)
+ 
+#pragma omp declare reduction (VecAppend : std::vector<int> : \
+    omp_out.insert(omp_out.end(), omp_in.begin(), omp_in.end())) \
+    initializer (omp_priv = omp_orig)
+
+//   Templates are  n o t  possible, i.e. the reduction has to be declared fore a specified type.
+//template <class T>
+//#pragma omp declare reduction(VecAdd : std::vector<T>  : omp_out += omp_in) initializer (omp_priv(omp_orig))
+// MS: template nach #pragma  !?
+
+// ------------------------------------------------------------
+
+
+/** 	Test for vector reduction.
+ * 
+ * The thread-private vectors of size @p n are initialized via @f$v_k^{tID}=tID+k@f$.
+ * Afterwards these vectors are accumulated, i.e., 
+ * @f$v_k= \sum_{tID=0}^{numThreads} v_k^{tID}@f$.
+ * 
+ * 	@param[in] n  size of global/private vector
+ * 	@return  resulting global vector.
+*/
+std::vector<int> reduction_vec(int n);
+
+
+/**	Test for vector reduction with appending the local vectors to a global
+ * 	size of global vector: n*#threads
+ * 
+ *  @param[in]	n	size of local/private vector
+ *  @return	resultign global vector
+ */
+std::vector<int> reduction_vec_append(int n);
+
+
+/** 	Output of a vector.
+	@param[in,out] s	output stream
+	@param[in]     x	vector
+	@return 	   modified output stream
+*/
+template <class T>
+std::ostream &operator<<(std::ostream &s, std::vector<T> const &x)
+{
+    for (auto const &v : x)  s << std::setw(4) << v << "  ";
+    return s;
+}
+