RealSvd2x2.h
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1 // This file is part of Eigen, a lightweight C++ template library
2 // for linear algebra.
3 //
4 // Copyright (C) 2009-2010 Benoit Jacob <jacob.benoit.1@gmail.com>
5 // Copyright (C) 2013-2016 Gael Guennebaud <gael.guennebaud@inria.fr>
6 //
7 // This Source Code Form is subject to the terms of the Mozilla
8 // Public License v. 2.0. If a copy of the MPL was not distributed
9 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
10 
11 #ifndef EIGEN_REALSVD2X2_H
12 #define EIGEN_REALSVD2X2_H
13 
14 namespace Eigen {
15 
16 namespace internal {
17 
18 template<typename MatrixType, typename RealScalar, typename Index>
22 {
23  using std::sqrt;
24  using std::abs;
26  m << numext::real(matrix.coeff(p,p)), numext::real(matrix.coeff(p,q)),
27  numext::real(matrix.coeff(q,p)), numext::real(matrix.coeff(q,q));
29  RealScalar t = m.coeff(0,0) + m.coeff(1,1);
30  RealScalar d = m.coeff(1,0) - m.coeff(0,1);
31 
33  {
34  rot1.s() = RealScalar(0);
35  rot1.c() = RealScalar(1);
36  }
37  else
38  {
39  // If d!=0, then t/d cannot overflow because the magnitude of the
40  // entries forming d are not too small compared to the ones forming t.
41  RealScalar u = t / d;
42  RealScalar tmp = sqrt(RealScalar(1) + numext::abs2(u));
43  rot1.s() = RealScalar(1) / tmp;
44  rot1.c() = u / tmp;
45  }
46  m.applyOnTheLeft(0,1,rot1);
47  j_right->makeJacobi(m,0,1);
48  *j_left = rot1 * j_right->transpose();
49 }
50 
51 } // end namespace internal
52 
53 } // end namespace Eigen
54 
55 #endif // EIGEN_REALSVD2X2_H
Matrix3f m
float real
Definition: datatypes.h:10
#define min(a, b)
Definition: datatypes.h:19
EIGEN_DEVICE_FUNC const SqrtReturnType sqrt() const
Namespace containing all symbols from the Eigen library.
Definition: jet.h:637
Rotation given by a cosine-sine pair.
MatrixXf MatrixType
bool makeJacobi(const MatrixBase< Derived > &, Index p, Index q)
Definition: Jacobi.h:126
JacobiRotation transpose() const
Definition: Jacobi.h:59
void real_2x2_jacobi_svd(const MatrixType &matrix, Index p, Index q, JacobiRotation< RealScalar > *j_left, JacobiRotation< RealScalar > *j_right)
Definition: RealSvd2x2.h:19
EIGEN_DEFAULT_DENSE_INDEX_TYPE Index
The Index type as used for the API.
Definition: Meta.h:33
EIGEN_DEVICE_FUNC const Scalar & q
NumTraits< Scalar >::Real RealScalar
Definition: bench_gemm.cpp:34
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE const Abs2ReturnType abs2() const
float * p
Map< Matrix< T, Dynamic, Dynamic, ColMajor >, 0, OuterStride<> > matrix(T *data, int rows, int cols, int stride)
The matrix class, also used for vectors and row-vectors.
#define abs(x)
Definition: datatypes.h:17
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE const Scalar & coeff(Index rowId, Index colId) const
Point2 t(10, 10)


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autogenerated on Sat May 8 2021 02:43:50