/*******************************************************************************
 *
 * TRIQS: a Toolbox for Research in Interacting Quantum Systems
 *
 * Copyright (C) 2011 by O. Parcollet
 *
 * TRIQS is free software: you can redistribute it and/or modify it under the
 * terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 *
 * TRIQS is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * TRIQS. If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/
#ifndef TRIQS_LINALG_CROSS_PRODUCT_H
#define TRIQS_LINALG_CROSS_PRODUCT_H
#include <triqs/utility/exceptions.hpp>

namespace triqs { namespace arrays { 

 /** Cross product. Dim 3 only */
 template<typename VectorType>
  vector<typename std::remove_const<typename VectorType::value_type >::type> 
  cross_product (VectorType const & A, VectorType const & B) { 
   if (A.shape()[0] !=3)  TRIQS_RUNTIME_ERROR<<"arrays::linalg::cross_product : works only in d=3 while you gave a vector of size "<<A.shape()[0];
   if (B.shape()[0] !=3)  TRIQS_RUNTIME_ERROR<<"arrays::linalg::cross_product : works only in d=3 while you gave a vector of size "<<B.shape()[0];
   vector<typename std::remove_const<typename VectorType::value_type >::type > r(3); 
   r(0) = A(1)* B(2) - B(1) * A(2);
   r(1) = - A(0)* B(2) + B(0) * A(2);
   r(2) = A(0)*B(1) - B(0) * A(1);
   return r;
  }

}}//namespace triqs::arrays 

#endif