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      1 // This file is part of Eigen, a lightweight C++ template library
      2 // for linear algebra.
      3 //
      4 // Copyright (C) 2012 Chen-Pang He <jdh8 (at) ms63.hinet.net>
      5 //
      6 // This Source Code Form is subject to the terms of the Mozilla
      7 // Public License v. 2.0. If a copy of the MPL was not distributed
      8 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
      9 
     10 #ifndef EIGEN_RANK2UPDATE_H
     11 #define EIGEN_RANK2UPDATE_H
     12 
     13 namespace internal {
     14 
     15 /* Optimized selfadjoint matrix += alpha * uv' + conj(alpha)*vu'
     16  * This is the low-level version of SelfadjointRank2Update.h
     17  */
     18 template<typename Scalar, typename Index, int UpLo>
     19 struct rank2_update_selector
     20 {
     21   static void run(Index size, Scalar* mat, Index stride, const Scalar* u, const Scalar* v, Scalar alpha)
     22   {
     23     typedef Map<const Matrix<Scalar,Dynamic,1> > OtherMap;
     24     for (Index i=0; i<size; ++i)
     25     {
     26       Map<Matrix<Scalar,Dynamic,1> >(mat+stride*i+(UpLo==Lower ? i : 0), UpLo==Lower ? size-i : (i+1)) +=
     27       numext::conj(alpha) * numext::conj(u[i]) * OtherMap(v+(UpLo==Lower ? i : 0), UpLo==Lower ? size-i : (i+1))
     28                 + alpha * numext::conj(v[i]) * OtherMap(u+(UpLo==Lower ? i : 0), UpLo==Lower ? size-i : (i+1));
     29     }
     30   }
     31 };
     32 
     33 /* Optimized selfadjoint matrix += alpha * uv' + conj(alpha)*vu'
     34  * The matrix is in packed form.
     35  */
     36 template<typename Scalar, typename Index, int UpLo>
     37 struct packed_rank2_update_selector
     38 {
     39   static void run(Index size, Scalar* mat, const Scalar* u, const Scalar* v, Scalar alpha)
     40   {
     41     typedef Map<const Matrix<Scalar,Dynamic,1> > OtherMap;
     42     Index offset = 0;
     43     for (Index i=0; i<size; ++i)
     44     {
     45       Map<Matrix<Scalar,Dynamic,1> >(mat+offset, UpLo==Lower ? size-i : (i+1)) +=
     46       numext::conj(alpha) * numext::conj(u[i]) * OtherMap(v+(UpLo==Lower ? i : 0), UpLo==Lower ? size-i : (i+1))
     47                 + alpha * numext::conj(v[i]) * OtherMap(u+(UpLo==Lower ? i : 0), UpLo==Lower ? size-i : (i+1));
     48       //FIXME This should be handled outside.
     49       mat[offset+(UpLo==Lower ? 0 : i)] = numext::real(mat[offset+(UpLo==Lower ? 0 : i)]);
     50       offset += UpLo==Lower ? size-i : (i+1);
     51     }
     52   }
     53 };
     54 
     55 } // end namespace internal
     56 
     57 #endif // EIGEN_RANK2UPDATE_H
     58