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78 lines
2.7 KiB
C++
78 lines
2.7 KiB
C++
// This file is part of Eigen, a lightweight C++ template library
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// for linear algebra. Eigen itself is part of the KDE project.
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//
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// Copyright (C) 2006-2008 Benoit Jacob <jacob@math.jussieu.fr>
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//
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// Eigen is free software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the Free Software
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// Foundation; either version 2 or (at your option) any later version.
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//
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// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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// details.
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//
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// You should have received a copy of the GNU General Public License along
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// with Eigen; if not, write to the Free Software Foundation, Inc., 51
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// Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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//
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// As a special exception, if other files instantiate templates or use macros
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// or functions from this file, or you compile this file and link it
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// with other works to produce a work based on this file, this file does not
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// by itself cause the resulting work to be covered by the GNU General Public
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// License. This exception does not invalidate any other reasons why a work
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// based on this file might be covered by the GNU General Public License.
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#ifndef EIGEN_TRACE_H
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#define EIGEN_TRACE_H
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template<int Index, int Rows, typename Derived> struct TraceUnroller
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{
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static void run(const Derived &mat, typename Derived::Scalar &trace)
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{
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TraceUnroller<Index-1, Rows, Derived>::run(mat, trace);
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trace += mat.coeff(Index, Index);
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}
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};
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template<int Rows, typename Derived> struct TraceUnroller<0, Rows, Derived>
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{
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static void run(const Derived &mat, typename Derived::Scalar &trace)
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{
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trace = mat.coeff(0, 0);
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}
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};
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template<int Index, typename Derived> struct TraceUnroller<Index, Dynamic, Derived>
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{
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static void run(const Derived&, typename Derived::Scalar&) {}
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};
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// prevent buggy user code from causing an infinite recursion
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template<int Index, typename Derived> struct TraceUnroller<Index, 0, Derived>
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{
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static void run(const Derived&, typename Derived::Scalar&) {}
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};
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/** \returns the trace of *this, which must be a square matrix.
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*
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* \sa diagonal() */
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template<typename Scalar, typename Derived>
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Scalar MatrixBase<Scalar, Derived>::trace() const
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{
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assert(rows() == cols());
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Scalar res;
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if(EIGEN_UNROLLED_LOOPS && Traits::RowsAtCompileTime != Dynamic && Traits::RowsAtCompileTime <= 16)
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TraceUnroller<Traits::RowsAtCompileTime-1, Traits::RowsAtCompileTime, Derived>
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::run(*static_cast<const Derived*>(this), res);
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else
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{
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res = coeff(0, 0);
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for(int i = 1; i < rows(); i++)
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res += coeff(i, i);
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}
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return res;
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}
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#endif // EIGEN_TRACE_H
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