text: //=================================================================================================
  /*!
  //  \file blaze/math/typetraits/IsCommutative.h
  //  \brief Header file for the IsCommutative type trait
  //
  //  Copyright (C) 2012-2020 Klaus Iglberger - All Rights Reserved
  //
  //  This file is part of the Blaze library. You can redistribute it and/or modify it under
  //  the terms of the New (Revised) BSD License. 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 names of the Blaze development group nor the names of its contributors
  //     may be used to endorse or promote products derived from this software without specific
  //     prior written permission.
  //
  //  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER OR 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.
  */
  //=================================================================================================
  
  #ifndef _BLAZE_MATH_TYPETRAITS_ISCOMMUTATIVE_H_
  #define _BLAZE_MATH_TYPETRAITS_ISCOMMUTATIVE_H_
  
  
  //*************************************************************************************************
  // Includes
  //*************************************************************************************************
  
  #include <blaze/math/typetraits/IsMatrix.h>
  #include <blaze/math/typetraits/IsVector.h>
  #include <blaze/math/typetraits/UnderlyingElement.h>
  #include <blaze/util/EnableIf.h>
  #include <blaze/util/IntegralConstant.h>
  #include <blaze/util/typetraits/IsNumeric.h>
  
  
  namespace blaze {
  
  //=================================================================================================
  //
  //  CLASS DEFINITION
  //
  //=================================================================================================
  
  //*************************************************************************************************
  /*!\brief Compile time check for the commutativity of data types.
  // \ingroup math_type_traits
  //
  // This type trait tests whether or not the two given data types \a T1 and T2 are commutative
  // with respect to mathematical operations. If the types are commutative, the \a value member
  // constant is set to \a true, the nested type definition \a Type is \a TrueType, and the class
  // derives from \a TrueType. Otherwise \a value is set to \a false, \a Type is \a FalseType,
  // and the class derives from \a FalseType.
  
     \code
     using VT = StaticVector<int,3UL>;
     using MT = StaticMatrix<int,3UL,3UL>;
  
     blaze::IsCommutative< double, complex<double> >::value                 // Evaluates to 1
     blaze::IsCommutative< DynamicVector<int>, DynamicVector<int> >::Type   // Results in TrueType
     blaze::IsCommutative< DynamicMatrix<VT>, DynamicMatrix<VT> >           // Is derived from TrueType
     blaze::IsCommutative< DynamicMatrix<int>, DynamicVector<int> >::value  // Evaluates to 0
     blaze::IsCommutative< DynamicVector<MT>, DynamicVector<VT> >::Type     // Results in FalseType
     blaze::IsCommutative< DynamicMatrix<VT>, DynamicMatrix<MT> >           // Is derived from FalseType
     \endcode
  */
  template< typename T1, typename T2, typename = void >
  struct IsCommutative
     : public BoolConstant< IsNumeric_v<T1> || IsNumeric_v<T2> >
  {};
  //*************************************************************************************************
  
  
  //*************************************************************************************************
  /*! \cond BLAZE_INTERNAL */
  /*!\brief Specialization of the IsCommutative type trait for vectors and matrices.
  // \ingroup math_type_traits
  */
  template< typename T1, typename T2 >
  struct IsCommutative< T1, T2
                      , EnableIf_t< ( IsVector_v<T1> && IsVector_v<T2> ) ||
                                    ( IsMatrix_v<T1> && IsMatrix_v<T2> ) > >
     : public BoolConstant< IsCommutative< UnderlyingElement_t<T1>, UnderlyingElement_t<T2> >::value >
  {};
  /*! \endcond */
  //*************************************************************************************************
  
  
  //*************************************************************************************************
  /*!\brief Auxiliary variable template for the IsCommutative type trait.
  // \ingroup math_type_traits
  //
  // The IsCommutative_v variable template provides a convenient shortcut to access the nested
  // \a value of the IsCommutative class template. For instance, given the type1 \a T1 and T2
  // the following two statements are identical:
  
     \code
     constexpr bool value1 = blaze::IsCommutative<T1,T2>::value;
     constexpr bool value2 = blaze::IsCommutative_v<T1,T2>;
     \endcode
  */
  template< typename T1, typename T2 >
  constexpr bool IsCommutative_v = IsCommutative<T1,T2>::value;
  //*************************************************************************************************
  
  } // namespace blaze
  
  #endif
  