[do not merge] std::linalg accessors and transposed_layout

docs/libcudacxx/standard_api.rst

@@ -106,10 +106,19 @@ Feature availability:
    -  ``mdspan`` is feature complete in C++17 onwards.
    -  ``mdspan`` on msvc is only supported in C++20 and onwards.
 
+-  C++26 ``std::dims`` is available in C++17.
+
+-  C++26 ``std::linalg`` accessors, transposed layout, and related functions are available in C++17.
+
+   - ``scaled()`` and ``scaled_accessor``
+   - ``conjugated()`` and ``conjugated_accessor``
+   - ``transposed()`` and ``layout_transpose``
+   - ``conjugate_transposed()``
+
 -  C++23 ``forward_like`` and ``to_underlying`` from ``<utility>`` are available in C++11.
 
 -  C++23 ``is_scoped_enum`` in ``<type_traits>`` is available in C++11.
 
--  C++26 ``std::dims`` is available in C++17.
+-  C++23 ``to_underlying`` from ``<utility>`` is available in C++11.
 
 -  C++26 tuple protocol to ``complex`` is available in C++11.

docs/libcudacxx/standard_api/numerics_library.rst

@@ -10,6 +10,7 @@ Numerics Library
    numerics_library/bit
    numerics_library/complex
    numerics_library/numeric
+   numerics_library/linalg
 
 Any Standard C++ header not listed below is omitted.
 

docs/libcudacxx/standard_api/numerics_library/linalg.rst

@@ -0,0 +1,31 @@
+.. _libcudacxx-standard-api-numerics-linalg:
+
+``<cuda/std/linalg>``
+============================================
+
+Provided functionalities
+------------------------
+
+- ``scaled()`` `std::linalg::scaled <https://en.cppreference.com/w/cpp/numeric/linalg/scaled>`_
+- ``scaled_accessor`` `std::linalg::scaled_accessor <https://en.cppreference.com/w/cpp/numeric/linalg/scaled_accessor>`_
+- ``conjugated()`` `std::linalg::conjugated <https://en.cppreference.com/w/cpp/numeric/linalg/conjugated>`_
+- ``conjugated_accessor`` `std::linalg::conjugated_accessor <https://en.cppreference.com/w/cpp/numeric/linalg/conjugated_accessor>`_
+- ``transposed()`` `std::linalg::transposed <https://en.cppreference.com/w/cpp/numeric/linalg/transposed>`_
+- ``layout_transpose`` `std::linalg::layout_transpose <https://en.cppreference.com/w/cpp/numeric/linalg/layout_transpose>`_
+- ``conjugate_transposed()`` `std::linalg::conjugate_transposed <https://en.cppreference.com/w/cpp/numeric/linalg/conjugate_transposed>`_
+
+Extensions
+----------
+
+-  C++26 ``std::linalg`` accessors, transposed layout, and related functions are available in C++17
+
+Omissions
+---------
+
+-  Currently we do not expose any BLAS functions and layouts.
+
+Restrictions
+------------
+
+-  On device no exceptions are thrown in case of a bad access.
+-  MSVC is only supported with C++20

libcudacxx/include/cuda/std/__linalg/conj_if_needed.h

@@ -0,0 +1,106 @@
+/*
+//@HEADER
+// ************************************************************************
+//
+//                        Kokkos v. 2.0
+//              Copyright (2019) Sandia Corporation
+//
+// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
+// the U.S. Government retains certain rights in this software. //
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// 1. Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution.
+//
+// 3. Neither the name of the Corporation nor the names of the
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SANDIA CORPORATION OR THE
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Questions? Contact Christian R. Trott (crtrott@sandia.gov)
+//
+// ************************************************************************
+//@HEADER
+*/
+#ifndef _LIBCUDACXX___LINALG_CONJUGATE_IF_NEEDED_HPP
+#define _LIBCUDACXX___LINALG_CONJUGATE_IF_NEEDED_HPP
+
+#include <cuda/std/detail/__config>
+
+#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
+#  pragma GCC system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
+#  pragma clang system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
+#  pragma system_header
+#endif // no system header
+
+#include <cuda/std/version>
+
+#if defined(__cccl_lib_mdspan) && _CCCL_STD_VER >= 2017
+
+#  include <cuda/std/__concepts/concept_macros.h>
+#  include <cuda/std/__type_traits/integral_constant.h>
+#  include <cuda/std/__type_traits/is_arithmetic.h>
+#  include <cuda/std/__type_traits/remove_const.h>
+#  include <cuda/std/__type_traits/void_t.h>
+#  include <cuda/std/__utility/declval.h>
+#  include <cuda/std/complex>
+
+_LIBCUDACXX_BEGIN_NAMESPACE_STD
+
+namespace linalg
+{
+
+_LIBCUDACXX_BEGIN_NAMESPACE_CPO(__conj_if_needed)
+
+template <class _Type>
+_CCCL_CONCEPT _HasConj = _CCCL_REQUIRES_EXPR((_Type), _Type __a)(static_cast<void>(_CUDA_VSTD::conj(__a)));
+
+struct __conj_if_needed
+{
+  template <class _Type>
+  _LIBCUDACXX_HIDE_FROM_ABI constexpr auto operator()(const _Type& __t) const
+  {
+    if constexpr (is_arithmetic_v<_Type> || !_HasConj<_Type>)
+    {
+      return __t;
+    }
+    else
+    {
+      return _CUDA_VSTD::conj(__t);
+    }
+    _CCCL_UNREACHABLE();
+  }
+};
+
+_LIBCUDACXX_END_NAMESPACE_CPO
+
+inline namespace __cpo
+{
+_CCCL_GLOBAL_CONSTANT auto conj_if_needed = __conj_if_needed::__conj_if_needed{};
+
+} // namespace __cpo
+} // end namespace linalg
+
+_LIBCUDACXX_END_NAMESPACE_STD
+
+#endif // defined(__cccl_lib_mdspan) && _CCCL_STD_VER >= 2017
+#endif // _LIBCUDACXX___LINALG_CONJUGATED_HPP

libcudacxx/include/cuda/std/__linalg/conjugate_transposed.h

@@ -0,0 +1,79 @@
+/*
+//@HEADER
+// ************************************************************************
+//
+//                        Kokkos v. 2.0
+//              Copyright (2019) Sandia Corporation
+//
+// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
+// the U.S. Government retains certain rights in this software. //
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// 1. Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution.
+//
+// 3. Neither the name of the Corporation nor the names of the
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SANDIA CORPORATION OR THE
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Questions? Contact Christian R. Trott (crtrott@sandia.gov)
+//
+// ************************************************************************
+//@HEADER
+*/
+#ifndef _LIBCUDACXX___LINALG_CONJUGATE_TRANSPOSED_HPP
+#define _LIBCUDACXX___LINALG_CONJUGATE_TRANSPOSED_HPP
+
+#include <cuda/std/detail/__config>
+
+#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
+#  pragma GCC system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
+#  pragma clang system_header
+#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
+#  pragma system_header
+#endif // no system header
+
+#include <cuda/std/version>
+
+#if defined(__cccl_lib_mdspan) && _CCCL_STD_VER >= 2017
+
+#  include <cuda/std/__linalg/conjugated.h>
+#  include <cuda/std/__linalg/transposed.h>
+
+_LIBCUDACXX_BEGIN_NAMESPACE_STD
+
+namespace linalg
+{
+
+template <class _ElementType, class _Extents, class _Layout, class _Accessor>
+_CCCL_NODISCARD _LIBCUDACXX_HIDE_FROM_ABI auto
+conjugate_transposed(mdspan<_ElementType, _Extents, _Layout, _Accessor> __a)
+{
+  return conjugated(transposed(__a));
+}
+
+} // end namespace linalg
+
+_LIBCUDACXX_END_NAMESPACE_STD
+
+#endif // defined(__cccl_lib_mdspan) && _CCCL_STD_VER >= 2017
+#endif // _LIBCUDACXX___LINALG_CONJUGATE_TRANSPOSED_HPP