customization: vector_norm_2: kokkos tpl hook and example kokkos#96

examples/kokkos-based/vector_norm2_kokkos.cpp

@@ -0,0 +1,34 @@
+
+#include <experimental/linalg>
+#include <iostream>
+
+int main(int argc, char* argv[])
+{
+  std::cout << "vector_norm2 example: calling kokkos-kernels" << std::endl;
+
+  std::size_t N = 20;
+  Kokkos::initialize(argc,argv);
+  {
+    using value_type = double;
+    Kokkos::View<value_type*> x_view("x",N);
+    value_type* x_ptr = x_view.data();
+
+    using dyn_1d_ext_type = std::experimental::extents<std::experimental::dynamic_extent>;
+    using mdspan_type  = std::experimental::mdspan<value_type, dyn_1d_ext_type>;
+    mdspan_type x(x_ptr,N);
+    for(std::size_t i=0; i<x.extent(0); i++){
+      x(i) = (value_type) i;
+    }
+
+    namespace stdla = std::experimental::linalg;
+    const value_type init_value(2);
+
+    const auto res = stdla::vector_norm2(x, init_value);
+    printf("Default result    = %lf\n", res);
+
+    const auto res_kk = stdla::vector_norm2(KokkosKernelsSTD::kokkos_exec<>(), x, init_value);
+    printf("Kokkos result = %lf\n", res_kk);
+
+  }
+  Kokkos::finalize();
+}

include/experimental/__p1673_bits/blas1_vector_norm2.hpp

@@ -73,9 +73,7 @@ struct is_custom_vector_norm2_avail<
   >
 {
   static constexpr bool value =
-    !std::is_same<Exec,
-		  std::experimental::linalg::impl::inline_exec_t
-		  >::value;
+    !std::is_same<Exec, std::experimental::linalg::impl::inline_exec_t>::value;
 };
 } // end anonymous namespace
 

tpl-implementations/include/experimental/__p1673_bits/kokkos-kernels/blas1_vector_norm2_kk.hpp

@@ -0,0 +1,21 @@
+
+#ifndef LINALG_TPLIMPLEMENTATIONS_INCLUDE_EXPERIMENTAL_P1673_BITS_KOKKOSKERNELS_VEC_NORM2_HPP_
+#define LINALG_TPLIMPLEMENTATIONS_INCLUDE_EXPERIMENTAL_P1673_BITS_KOKKOSKERNELS_VEC_NORM2_HPP_
+
+namespace KokkosKernelsSTD {
+
+template<class ExecSpace,
+         class ElementType,
+	 std::experimental::extents<>::size_type ext0,
+         class Layout,
+         class Accessor,
+         class Scalar>
+Scalar vector_norm2(kokkos_exec<ExecSpace>,
+		    std::experimental::mdspan<ElementType, std::experimental::extents<ext0>, Layout, Accessor> v,
+		    Scalar init)
+{
+  return init + KokkosBlas::nrm2(Impl::mdspan_to_view(v));
+}
+
+}
+#endif