118 lines
3.4 KiB
C++
118 lines
3.4 KiB
C++
// This file is part of Eigen, a lightweight C++ template library
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// for linear algebra.
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//
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// Copyright (C) 2008 Benoit Jacob <jacob.benoit.1@gmail.com>
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//
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// This Source Code Form is subject to the terms of the Mozilla
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// Public License v. 2.0. If a copy of the MPL was not distributed
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// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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#ifndef EIGEN_DETERMINANT_H
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#define EIGEN_DETERMINANT_H
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namespace Eigen {
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namespace internal {
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template<typename Derived>
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EIGEN_DEVICE_FUNC
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inline const typename Derived::Scalar bruteforce_det3_helper
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(const MatrixBase<Derived>& matrix, int a, int b, int c)
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{
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return matrix.coeff(0,a)
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* (matrix.coeff(1,b) * matrix.coeff(2,c) - matrix.coeff(1,c) * matrix.coeff(2,b));
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}
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template<typename Derived,
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int DeterminantType = Derived::RowsAtCompileTime
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> struct determinant_impl
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{
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static inline typename traits<Derived>::Scalar run(const Derived& m)
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{
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if(Derived::ColsAtCompileTime==Dynamic && m.rows()==0)
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return typename traits<Derived>::Scalar(1);
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return m.partialPivLu().determinant();
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}
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};
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template<typename Derived> struct determinant_impl<Derived, 1>
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{
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static inline EIGEN_DEVICE_FUNC
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typename traits<Derived>::Scalar run(const Derived& m)
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{
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return m.coeff(0,0);
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}
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};
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template<typename Derived> struct determinant_impl<Derived, 2>
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{
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static inline EIGEN_DEVICE_FUNC
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typename traits<Derived>::Scalar run(const Derived& m)
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{
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return m.coeff(0,0) * m.coeff(1,1) - m.coeff(1,0) * m.coeff(0,1);
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}
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};
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template<typename Derived> struct determinant_impl<Derived, 3>
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{
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static inline EIGEN_DEVICE_FUNC
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typename traits<Derived>::Scalar run(const Derived& m)
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{
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return bruteforce_det3_helper(m,0,1,2)
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- bruteforce_det3_helper(m,1,0,2)
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+ bruteforce_det3_helper(m,2,0,1);
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}
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};
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template<typename Derived> struct determinant_impl<Derived, 4>
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{
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typedef typename traits<Derived>::Scalar Scalar;
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static EIGEN_DEVICE_FUNC
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Scalar run(const Derived& m)
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{
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Scalar d2_01 = det2(m, 0, 1);
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Scalar d2_02 = det2(m, 0, 2);
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Scalar d2_03 = det2(m, 0, 3);
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Scalar d2_12 = det2(m, 1, 2);
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Scalar d2_13 = det2(m, 1, 3);
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Scalar d2_23 = det2(m, 2, 3);
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Scalar d3_0 = det3(m, 1,d2_23, 2,d2_13, 3,d2_12);
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Scalar d3_1 = det3(m, 0,d2_23, 2,d2_03, 3,d2_02);
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Scalar d3_2 = det3(m, 0,d2_13, 1,d2_03, 3,d2_01);
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Scalar d3_3 = det3(m, 0,d2_12, 1,d2_02, 2,d2_01);
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return internal::pmadd(-m(0,3),d3_0, m(1,3)*d3_1) +
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internal::pmadd(-m(2,3),d3_2, m(3,3)*d3_3);
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}
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protected:
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static EIGEN_DEVICE_FUNC
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Scalar det2(const Derived& m, Index i0, Index i1)
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{
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return m(i0,0) * m(i1,1) - m(i1,0) * m(i0,1);
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}
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static EIGEN_DEVICE_FUNC
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Scalar det3(const Derived& m, Index i0, const Scalar& d0, Index i1, const Scalar& d1, Index i2, const Scalar& d2)
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{
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return internal::pmadd(m(i0,2), d0, internal::pmadd(-m(i1,2), d1, m(i2,2)*d2));
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}
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};
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} // end namespace internal
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/** \lu_module
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*
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* \returns the determinant of this matrix
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*/
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template<typename Derived>
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EIGEN_DEVICE_FUNC
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inline typename internal::traits<Derived>::Scalar MatrixBase<Derived>::determinant() const
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{
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eigen_assert(rows() == cols());
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typedef typename internal::nested_eval<Derived,Base::RowsAtCompileTime>::type Nested;
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return internal::determinant_impl<typename internal::remove_all<Nested>::type>::run(derived());
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}
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} // end namespace Eigen
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#endif // EIGEN_DETERMINANT_H
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