implement batched serial iamax

batched/dense/impl/KokkosBatched_Iamax_Serial_Impl.hpp

@@ -0,0 +1,37 @@
+//@HEADER
+// ************************************************************************
+//
+//                        Kokkos v. 4.0
+//       Copyright (2022) National Technology & Engineering
+//               Solutions of Sandia, LLC (NTESS).
+//
+// Under the terms of Contract DE-NA0003525 with NTESS,
+// the U.S. Government retains certain rights in this software.
+//
+// Part of Kokkos, under the Apache License v2.0 with LLVM Exceptions.
+// See https://kokkos.org/LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//@HEADER
+
+#ifndef KOKKOSBATCHED_IAMAX_SERIAL_IMPL_HPP_
+#define KOKKOSBATCHED_IAMAX_SERIAL_IMPL_HPP_
+
+/// \author Yuuichi Asahi ([email protected])
+
+#include "KokkosBatched_Iamax_Serial_Internal.hpp"
+
+namespace KokkosBatched {
+
+template <typename XViewType>
+KOKKOS_INLINE_FUNCTION typename XViewType::size_type SerialIamax::invoke(const XViewType &x) {
+  static_assert(Kokkos::is_view_v<XViewType>, "KokkosBatched::iamax: XViewType is not a Kokkos::View.");
+  if (x.extent(0) <= 1) return 0;
+  using size_type  = typename XViewType::size_type;
+  using value_type = typename XViewType::non_const_value_type;
+  return KokkosBatched::Impl::SerialIamaxInternal::invoke<size_type, value_type>(x.extent(0), x.data(), x.stride(0));
+}
+
+}  // namespace KokkosBatched
+
+#endif  // KOKKOSBATCHED_IAMAX_SERIAL_IMPL_HPP_

batched/dense/impl/KokkosBatched_Iamax_Serial_Internal.hpp

@@ -0,0 +1,60 @@
+//@HEADER
+// ************************************************************************
+//
+//                        Kokkos v. 4.0
+//       Copyright (2022) National Technology & Engineering
+//               Solutions of Sandia, LLC (NTESS).
+//
+// Under the terms of Contract DE-NA0003525 with NTESS,
+// the U.S. Government retains certain rights in this software.
+//
+// Part of Kokkos, under the Apache License v2.0 with LLVM Exceptions.
+// See https://kokkos.org/LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//@HEADER
+
+#ifndef KOKKOSBATCHED_IAMAX_SERIAL_INTERNAL_HPP_
+#define KOKKOSBATCHED_IAMAX_SERIAL_INTERNAL_HPP_
+
+/// \author Yuuichi Asahi ([email protected])
+
+#include <Kokkos_Core.hpp>
+#include "KokkosBatched_Util.hpp"
+
+namespace KokkosBatched {
+namespace Impl {
+
+///
+/// Serial Internal Impl
+/// ========================
+
+struct SerialIamaxInternal {
+  template <typename IndexType, typename ValueType>
+  KOKKOS_INLINE_FUNCTION static IndexType invoke(const int n, const ValueType *KOKKOS_RESTRICT x, const int xs0);
+};
+
+template <typename IndexType, typename ValueType>
+KOKKOS_INLINE_FUNCTION IndexType SerialIamaxInternal::invoke(const int n, const ValueType *KOKKOS_RESTRICT x,
+                                                             const int xs0) {
+  using ats      = typename Kokkos::ArithTraits<ValueType>;
+  using RealType = typename ats::mag_type;
+
+  RealType amax  = Kokkos::abs(x[0 * xs0]);
+  IndexType imax = 0;
+
+  for (IndexType i = 1; i < static_cast<IndexType>(n); ++i) {
+    const RealType abs_x_i = Kokkos::abs(x[i * xs0]);
+    if (abs_x_i > amax) {
+      amax = abs_x_i;
+      imax = i;
+    }
+  }
+
+  return imax;
+};
+
+}  // namespace Impl
+}  // namespace KokkosBatched
+
+#endif  // KOKKOSBATCHED_IAMAX_SERIAL_INTERNAL_HPP_

batched/dense/src/KokkosBatched_Iamax.hpp

@@ -0,0 +1,43 @@
+//@HEADER
+// ************************************************************************
+//
+//                        Kokkos v. 4.0
+//       Copyright (2022) National Technology & Engineering
+//               Solutions of Sandia, LLC (NTESS).
+//
+// Under the terms of Contract DE-NA0003525 with NTESS,
+// the U.S. Government retains certain rights in this software.
+//
+// Part of Kokkos, under the Apache License v2.0 with LLVM Exceptions.
+// See https://kokkos.org/LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//@HEADER
+#ifndef KOKKOSBATCHED_IAMAX_HPP_
+#define KOKKOSBATCHED_IAMAX_HPP_
+
+/// \author Yuuichi Asahi ([email protected])
+
+namespace KokkosBatched {
+
+/// \brief Serial Batched Iamax:
+/// Iamax finds the index of the first element having maximum absolute value.
+///
+/// \tparam XViewType: Input view type, needs to be a 1D view
+///
+/// \param X [in]: Input view type
+///
+/// \return The index of the first element having maximum absolute value
+/// As well as Blas, this returns 0 (0 in Fortran) for an empty vector
+/// No nested parallel_for is used inside of the function.
+///
+
+struct SerialIamax {
+  template <typename XViewType>
+  KOKKOS_INLINE_FUNCTION static typename XViewType::size_type invoke(const XViewType &x);
+};
+}  // namespace KokkosBatched
+
+#include "KokkosBatched_Iamax_Serial_Impl.hpp"
+
+#endif  // KOKKOSBATCHED_IAMAX_HPP_

batched/dense/unit_test/Test_Batched_Dense.hpp

@@ -62,6 +62,7 @@
 #include "Test_Batched_SerialPbtrs_Real.hpp"
 #include "Test_Batched_SerialPbtrs_Complex.hpp"
 #include "Test_Batched_SerialLaswp.hpp"
+#include "Test_Batched_SerialIamax.hpp"
 
 // Team Kernels
 #include "Test_Batched_TeamAxpy.hpp"