xref: /aosp_15_r20/external/eigen/unsupported/Eigen/src/Eigenvalues/ArpackSelfAdjointEigenSolver.h (revision bf2c37156dfe67e5dfebd6d394bad8b2ab5804d4)
1 // This file is part of Eigen, a lightweight C++ template library
2 // for linear algebra.
3 //
4 // Copyright (C) 2012 David Harmon <[email protected]>
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_ARPACKGENERALIZEDSELFADJOINTEIGENSOLVER_H
11 #define EIGEN_ARPACKGENERALIZEDSELFADJOINTEIGENSOLVER_H
12 
13 #include "../../../../Eigen/Dense"
14 
15 namespace Eigen {
16 
17 namespace internal {
18   template<typename Scalar, typename RealScalar> struct arpack_wrapper;
19   template<typename MatrixSolver, typename MatrixType, typename Scalar, bool BisSPD> struct OP;
20 }
21 
22 
23 
24 template<typename MatrixType, typename MatrixSolver=SimplicialLLT<MatrixType>, bool BisSPD=false>
25 class ArpackGeneralizedSelfAdjointEigenSolver
26 {
27 public:
28   //typedef typename MatrixSolver::MatrixType MatrixType;
29 
30   /** \brief Scalar type for matrices of type \p MatrixType. */
31   typedef typename MatrixType::Scalar Scalar;
32   typedef typename MatrixType::Index Index;
33 
34   /** \brief Real scalar type for \p MatrixType.
35    *
36    * This is just \c Scalar if #Scalar is real (e.g., \c float or
37    * \c Scalar), and the type of the real part of \c Scalar if #Scalar is
38    * complex.
39    */
40   typedef typename NumTraits<Scalar>::Real RealScalar;
41 
42   /** \brief Type for vector of eigenvalues as returned by eigenvalues().
43    *
44    * This is a column vector with entries of type #RealScalar.
45    * The length of the vector is the size of \p nbrEigenvalues.
46    */
47   typedef typename internal::plain_col_type<MatrixType, RealScalar>::type RealVectorType;
48 
49   /** \brief Default constructor.
50    *
51    * The default constructor is for cases in which the user intends to
52    * perform decompositions via compute().
53    *
54    */
ArpackGeneralizedSelfAdjointEigenSolver()55   ArpackGeneralizedSelfAdjointEigenSolver()
56    : m_eivec(),
57      m_eivalues(),
58      m_isInitialized(false),
59      m_eigenvectorsOk(false),
60      m_nbrConverged(0),
61      m_nbrIterations(0)
62   { }
63 
64   /** \brief Constructor; computes generalized eigenvalues of given matrix with respect to another matrix.
65    *
66    * \param[in] A Self-adjoint matrix whose eigenvalues / eigenvectors will
67    *    computed. By default, the upper triangular part is used, but can be changed
68    *    through the template parameter.
69    * \param[in] B Self-adjoint matrix for the generalized eigenvalue problem.
70    * \param[in] nbrEigenvalues The number of eigenvalues / eigenvectors to compute.
71    *    Must be less than the size of the input matrix, or an error is returned.
72    * \param[in] eigs_sigma String containing either "LM", "SM", "LA", or "SA", with
73    *    respective meanings to find the largest magnitude , smallest magnitude,
74    *    largest algebraic, or smallest algebraic eigenvalues. Alternatively, this
75    *    value can contain floating point value in string form, in which case the
76    *    eigenvalues closest to this value will be found.
77    * \param[in]  options Can be #ComputeEigenvectors (default) or #EigenvaluesOnly.
78    * \param[in] tol What tolerance to find the eigenvalues to. Default is 0, which
79    *    means machine precision.
80    *
81    * This constructor calls compute(const MatrixType&, const MatrixType&, Index, string, int, RealScalar)
82    * to compute the eigenvalues of the matrix \p A with respect to \p B. The eigenvectors are computed if
83    * \p options equals #ComputeEigenvectors.
84    *
85    */
86   ArpackGeneralizedSelfAdjointEigenSolver(const MatrixType& A, const MatrixType& B,
87                                           Index nbrEigenvalues, std::string eigs_sigma="LM",
88                                int options=ComputeEigenvectors, RealScalar tol=0.0)
m_eivec()89     : m_eivec(),
90       m_eivalues(),
91       m_isInitialized(false),
92       m_eigenvectorsOk(false),
93       m_nbrConverged(0),
94       m_nbrIterations(0)
95   {
96     compute(A, B, nbrEigenvalues, eigs_sigma, options, tol);
97   }
98 
99   /** \brief Constructor; computes eigenvalues of given matrix.
100    *
101    * \param[in] A Self-adjoint matrix whose eigenvalues / eigenvectors will
102    *    computed. By default, the upper triangular part is used, but can be changed
103    *    through the template parameter.
104    * \param[in] nbrEigenvalues The number of eigenvalues / eigenvectors to compute.
105    *    Must be less than the size of the input matrix, or an error is returned.
106    * \param[in] eigs_sigma String containing either "LM", "SM", "LA", or "SA", with
107    *    respective meanings to find the largest magnitude , smallest magnitude,
108    *    largest algebraic, or smallest algebraic eigenvalues. Alternatively, this
109    *    value can contain floating point value in string form, in which case the
110    *    eigenvalues closest to this value will be found.
111    * \param[in]  options Can be #ComputeEigenvectors (default) or #EigenvaluesOnly.
112    * \param[in] tol What tolerance to find the eigenvalues to. Default is 0, which
113    *    means machine precision.
114    *
115    * This constructor calls compute(const MatrixType&, Index, string, int, RealScalar)
116    * to compute the eigenvalues of the matrix \p A. The eigenvectors are computed if
117    * \p options equals #ComputeEigenvectors.
118    *
119    */
120 
121   ArpackGeneralizedSelfAdjointEigenSolver(const MatrixType& A,
122                                           Index nbrEigenvalues, std::string eigs_sigma="LM",
123                                int options=ComputeEigenvectors, RealScalar tol=0.0)
m_eivec()124     : m_eivec(),
125       m_eivalues(),
126       m_isInitialized(false),
127       m_eigenvectorsOk(false),
128       m_nbrConverged(0),
129       m_nbrIterations(0)
130   {
131     compute(A, nbrEigenvalues, eigs_sigma, options, tol);
132   }
133 
134 
135   /** \brief Computes generalized eigenvalues / eigenvectors of given matrix using the external ARPACK library.
136    *
137    * \param[in]  A  Selfadjoint matrix whose eigendecomposition is to be computed.
138    * \param[in]  B  Selfadjoint matrix for generalized eigenvalues.
139    * \param[in] nbrEigenvalues The number of eigenvalues / eigenvectors to compute.
140    *    Must be less than the size of the input matrix, or an error is returned.
141    * \param[in] eigs_sigma String containing either "LM", "SM", "LA", or "SA", with
142    *    respective meanings to find the largest magnitude , smallest magnitude,
143    *    largest algebraic, or smallest algebraic eigenvalues. Alternatively, this
144    *    value can contain floating point value in string form, in which case the
145    *    eigenvalues closest to this value will be found.
146    * \param[in]  options Can be #ComputeEigenvectors (default) or #EigenvaluesOnly.
147    * \param[in] tol What tolerance to find the eigenvalues to. Default is 0, which
148    *    means machine precision.
149    *
150    * \returns    Reference to \c *this
151    *
152    * This function computes the generalized eigenvalues of \p A with respect to \p B using ARPACK.  The eigenvalues()
153    * function can be used to retrieve them.  If \p options equals #ComputeEigenvectors,
154    * then the eigenvectors are also computed and can be retrieved by
155    * calling eigenvectors().
156    *
157    */
158   ArpackGeneralizedSelfAdjointEigenSolver& compute(const MatrixType& A, const MatrixType& B,
159                                                    Index nbrEigenvalues, std::string eigs_sigma="LM",
160                                         int options=ComputeEigenvectors, RealScalar tol=0.0);
161 
162   /** \brief Computes eigenvalues / eigenvectors of given matrix using the external ARPACK library.
163    *
164    * \param[in]  A  Selfadjoint matrix whose eigendecomposition is to be computed.
165    * \param[in] nbrEigenvalues The number of eigenvalues / eigenvectors to compute.
166    *    Must be less than the size of the input matrix, or an error is returned.
167    * \param[in] eigs_sigma String containing either "LM", "SM", "LA", or "SA", with
168    *    respective meanings to find the largest magnitude , smallest magnitude,
169    *    largest algebraic, or smallest algebraic eigenvalues. Alternatively, this
170    *    value can contain floating point value in string form, in which case the
171    *    eigenvalues closest to this value will be found.
172    * \param[in]  options Can be #ComputeEigenvectors (default) or #EigenvaluesOnly.
173    * \param[in] tol What tolerance to find the eigenvalues to. Default is 0, which
174    *    means machine precision.
175    *
176    * \returns    Reference to \c *this
177    *
178    * This function computes the eigenvalues of \p A using ARPACK.  The eigenvalues()
179    * function can be used to retrieve them.  If \p options equals #ComputeEigenvectors,
180    * then the eigenvectors are also computed and can be retrieved by
181    * calling eigenvectors().
182    *
183    */
184   ArpackGeneralizedSelfAdjointEigenSolver& compute(const MatrixType& A,
185                                                    Index nbrEigenvalues, std::string eigs_sigma="LM",
186                                         int options=ComputeEigenvectors, RealScalar tol=0.0);
187 
188 
189   /** \brief Returns the eigenvectors of given matrix.
190    *
191    * \returns  A const reference to the matrix whose columns are the eigenvectors.
192    *
193    * \pre The eigenvectors have been computed before.
194    *
195    * Column \f$ k \f$ of the returned matrix is an eigenvector corresponding
196    * to eigenvalue number \f$ k \f$ as returned by eigenvalues().  The
197    * eigenvectors are normalized to have (Euclidean) norm equal to one. If
198    * this object was used to solve the eigenproblem for the selfadjoint
199    * matrix \f$ A \f$, then the matrix returned by this function is the
200    * matrix \f$ V \f$ in the eigendecomposition \f$ A V = D V \f$.
201    * For the generalized eigenproblem, the matrix returned is the solution \f$ A V = D B V \f$
202    *
203    * Example: \include SelfAdjointEigenSolver_eigenvectors.cpp
204    * Output: \verbinclude SelfAdjointEigenSolver_eigenvectors.out
205    *
206    * \sa eigenvalues()
207    */
eigenvectors()208   const Matrix<Scalar, Dynamic, Dynamic>& eigenvectors() const
209   {
210     eigen_assert(m_isInitialized && "ArpackGeneralizedSelfAdjointEigenSolver is not initialized.");
211     eigen_assert(m_eigenvectorsOk && "The eigenvectors have not been computed together with the eigenvalues.");
212     return m_eivec;
213   }
214 
215   /** \brief Returns the eigenvalues of given matrix.
216    *
217    * \returns A const reference to the column vector containing the eigenvalues.
218    *
219    * \pre The eigenvalues have been computed before.
220    *
221    * The eigenvalues are repeated according to their algebraic multiplicity,
222    * so there are as many eigenvalues as rows in the matrix. The eigenvalues
223    * are sorted in increasing order.
224    *
225    * Example: \include SelfAdjointEigenSolver_eigenvalues.cpp
226    * Output: \verbinclude SelfAdjointEigenSolver_eigenvalues.out
227    *
228    * \sa eigenvectors(), MatrixBase::eigenvalues()
229    */
eigenvalues()230   const Matrix<Scalar, Dynamic, 1>& eigenvalues() const
231   {
232     eigen_assert(m_isInitialized && "ArpackGeneralizedSelfAdjointEigenSolver is not initialized.");
233     return m_eivalues;
234   }
235 
236   /** \brief Computes the positive-definite square root of the matrix.
237    *
238    * \returns the positive-definite square root of the matrix
239    *
240    * \pre The eigenvalues and eigenvectors of a positive-definite matrix
241    * have been computed before.
242    *
243    * The square root of a positive-definite matrix \f$ A \f$ is the
244    * positive-definite matrix whose square equals \f$ A \f$. This function
245    * uses the eigendecomposition \f$ A = V D V^{-1} \f$ to compute the
246    * square root as \f$ A^{1/2} = V D^{1/2} V^{-1} \f$.
247    *
248    * Example: \include SelfAdjointEigenSolver_operatorSqrt.cpp
249    * Output: \verbinclude SelfAdjointEigenSolver_operatorSqrt.out
250    *
251    * \sa operatorInverseSqrt(),
252    *     \ref MatrixFunctions_Module "MatrixFunctions Module"
253    */
operatorSqrt()254   Matrix<Scalar, Dynamic, Dynamic> operatorSqrt() const
255   {
256     eigen_assert(m_isInitialized && "SelfAdjointEigenSolver is not initialized.");
257     eigen_assert(m_eigenvectorsOk && "The eigenvectors have not been computed together with the eigenvalues.");
258     return m_eivec * m_eivalues.cwiseSqrt().asDiagonal() * m_eivec.adjoint();
259   }
260 
261   /** \brief Computes the inverse square root of the matrix.
262    *
263    * \returns the inverse positive-definite square root of the matrix
264    *
265    * \pre The eigenvalues and eigenvectors of a positive-definite matrix
266    * have been computed before.
267    *
268    * This function uses the eigendecomposition \f$ A = V D V^{-1} \f$ to
269    * compute the inverse square root as \f$ V D^{-1/2} V^{-1} \f$. This is
270    * cheaper than first computing the square root with operatorSqrt() and
271    * then its inverse with MatrixBase::inverse().
272    *
273    * Example: \include SelfAdjointEigenSolver_operatorInverseSqrt.cpp
274    * Output: \verbinclude SelfAdjointEigenSolver_operatorInverseSqrt.out
275    *
276    * \sa operatorSqrt(), MatrixBase::inverse(),
277    *     \ref MatrixFunctions_Module "MatrixFunctions Module"
278    */
operatorInverseSqrt()279   Matrix<Scalar, Dynamic, Dynamic> operatorInverseSqrt() const
280   {
281     eigen_assert(m_isInitialized && "SelfAdjointEigenSolver is not initialized.");
282     eigen_assert(m_eigenvectorsOk && "The eigenvectors have not been computed together with the eigenvalues.");
283     return m_eivec * m_eivalues.cwiseInverse().cwiseSqrt().asDiagonal() * m_eivec.adjoint();
284   }
285 
286   /** \brief Reports whether previous computation was successful.
287    *
288    * \returns \c Success if computation was successful, \c NoConvergence otherwise.
289    */
info()290   ComputationInfo info() const
291   {
292     eigen_assert(m_isInitialized && "ArpackGeneralizedSelfAdjointEigenSolver is not initialized.");
293     return m_info;
294   }
295 
getNbrConvergedEigenValues()296   size_t getNbrConvergedEigenValues() const
297   { return m_nbrConverged; }
298 
getNbrIterations()299   size_t getNbrIterations() const
300   { return m_nbrIterations; }
301 
302 protected:
303   Matrix<Scalar, Dynamic, Dynamic> m_eivec;
304   Matrix<Scalar, Dynamic, 1> m_eivalues;
305   ComputationInfo m_info;
306   bool m_isInitialized;
307   bool m_eigenvectorsOk;
308 
309   size_t m_nbrConverged;
310   size_t m_nbrIterations;
311 };
312 
313 
314 
315 
316 
317 template<typename MatrixType, typename MatrixSolver, bool BisSPD>
318 ArpackGeneralizedSelfAdjointEigenSolver<MatrixType, MatrixSolver, BisSPD>&
319     ArpackGeneralizedSelfAdjointEigenSolver<MatrixType, MatrixSolver, BisSPD>
compute(const MatrixType & A,Index nbrEigenvalues,std::string eigs_sigma,int options,RealScalar tol)320 ::compute(const MatrixType& A, Index nbrEigenvalues,
321           std::string eigs_sigma, int options, RealScalar tol)
322 {
323     MatrixType B(0,0);
324     compute(A, B, nbrEigenvalues, eigs_sigma, options, tol);
325 
326     return *this;
327 }
328 
329 
330 template<typename MatrixType, typename MatrixSolver, bool BisSPD>
331 ArpackGeneralizedSelfAdjointEigenSolver<MatrixType, MatrixSolver, BisSPD>&
332     ArpackGeneralizedSelfAdjointEigenSolver<MatrixType, MatrixSolver, BisSPD>
compute(const MatrixType & A,const MatrixType & B,Index nbrEigenvalues,std::string eigs_sigma,int options,RealScalar tol)333 ::compute(const MatrixType& A, const MatrixType& B, Index nbrEigenvalues,
334           std::string eigs_sigma, int options, RealScalar tol)
335 {
336   eigen_assert(A.cols() == A.rows());
337   eigen_assert(B.cols() == B.rows());
338   eigen_assert(B.rows() == 0 || A.cols() == B.rows());
339   eigen_assert((options &~ (EigVecMask | GenEigMask)) == 0
340             && (options & EigVecMask) != EigVecMask
341             && "invalid option parameter");
342 
343   bool isBempty = (B.rows() == 0) || (B.cols() == 0);
344 
345   // For clarity, all parameters match their ARPACK name
346   //
347   // Always 0 on the first call
348   //
349   int ido = 0;
350 
351   int n = (int)A.cols();
352 
353   // User options: "LA", "SA", "SM", "LM", "BE"
354   //
355   char whch[3] = "LM";
356 
357   // Specifies the shift if iparam[6] = { 3, 4, 5 }, not used if iparam[6] = { 1, 2 }
358   //
359   RealScalar sigma = 0.0;
360 
361   if (eigs_sigma.length() >= 2 && isalpha(eigs_sigma[0]) && isalpha(eigs_sigma[1]))
362   {
363       eigs_sigma[0] = toupper(eigs_sigma[0]);
364       eigs_sigma[1] = toupper(eigs_sigma[1]);
365 
366       // In the following special case we're going to invert the problem, since solving
367       // for larger magnitude is much much faster
368       // i.e., if 'SM' is specified, we're going to really use 'LM', the default
369       //
370       if (eigs_sigma.substr(0,2) != "SM")
371       {
372           whch[0] = eigs_sigma[0];
373           whch[1] = eigs_sigma[1];
374       }
375   }
376   else
377   {
378       eigen_assert(false && "Specifying clustered eigenvalues is not yet supported!");
379 
380       // If it's not scalar values, then the user may be explicitly
381       // specifying the sigma value to cluster the evs around
382       //
383       sigma = atof(eigs_sigma.c_str());
384 
385       // If atof fails, it returns 0.0, which is a fine default
386       //
387   }
388 
389   // "I" means normal eigenvalue problem, "G" means generalized
390   //
391   char bmat[2] = "I";
392   if (eigs_sigma.substr(0,2) == "SM" || !(isalpha(eigs_sigma[0]) && isalpha(eigs_sigma[1])) || (!isBempty && !BisSPD))
393       bmat[0] = 'G';
394 
395   // Now we determine the mode to use
396   //
397   int mode = (bmat[0] == 'G') + 1;
398   if (eigs_sigma.substr(0,2) == "SM" || !(isalpha(eigs_sigma[0]) && isalpha(eigs_sigma[1])))
399   {
400       // We're going to use shift-and-invert mode, and basically find
401       // the largest eigenvalues of the inverse operator
402       //
403       mode = 3;
404   }
405 
406   // The user-specified number of eigenvalues/vectors to compute
407   //
408   int nev = (int)nbrEigenvalues;
409 
410   // Allocate space for ARPACK to store the residual
411   //
412   Scalar *resid = new Scalar[n];
413 
414   // Number of Lanczos vectors, must satisfy nev < ncv <= n
415   // Note that this indicates that nev != n, and we cannot compute
416   // all eigenvalues of a mtrix
417   //
418   int ncv = std::min(std::max(2*nev, 20), n);
419 
420   // The working n x ncv matrix, also store the final eigenvectors (if computed)
421   //
422   Scalar *v = new Scalar[n*ncv];
423   int ldv = n;
424 
425   // Working space
426   //
427   Scalar *workd = new Scalar[3*n];
428   int lworkl = ncv*ncv+8*ncv; // Must be at least this length
429   Scalar *workl = new Scalar[lworkl];
430 
431   int *iparam= new int[11];
432   iparam[0] = 1; // 1 means we let ARPACK perform the shifts, 0 means we'd have to do it
433   iparam[2] = std::max(300, (int)std::ceil(2*n/std::max(ncv,1)));
434   iparam[6] = mode; // The mode, 1 is standard ev problem, 2 for generalized ev, 3 for shift-and-invert
435 
436   // Used during reverse communicate to notify where arrays start
437   //
438   int *ipntr = new int[11];
439 
440   // Error codes are returned in here, initial value of 0 indicates a random initial
441   // residual vector is used, any other values means resid contains the initial residual
442   // vector, possibly from a previous run
443   //
444   int info = 0;
445 
446   Scalar scale = 1.0;
447   //if (!isBempty)
448   //{
449   //Scalar scale = B.norm() / std::sqrt(n);
450   //scale = std::pow(2, std::floor(std::log(scale+1)));
451   ////M /= scale;
452   //for (size_t i=0; i<(size_t)B.outerSize(); i++)
453   //    for (typename MatrixType::InnerIterator it(B, i); it; ++it)
454   //        it.valueRef() /= scale;
455   //}
456 
457   MatrixSolver OP;
458   if (mode == 1 || mode == 2)
459   {
460       if (!isBempty)
461           OP.compute(B);
462   }
463   else if (mode == 3)
464   {
465       if (sigma == 0.0)
466       {
467           OP.compute(A);
468       }
469       else
470       {
471           // Note: We will never enter here because sigma must be 0.0
472           //
473           if (isBempty)
474           {
475             MatrixType AminusSigmaB(A);
476             for (Index i=0; i<A.rows(); ++i)
477                 AminusSigmaB.coeffRef(i,i) -= sigma;
478 
479             OP.compute(AminusSigmaB);
480           }
481           else
482           {
483               MatrixType AminusSigmaB = A - sigma * B;
484               OP.compute(AminusSigmaB);
485           }
486       }
487   }
488 
489   if (!(mode == 1 && isBempty) && !(mode == 2 && isBempty) && OP.info() != Success)
490       std::cout << "Error factoring matrix" << std::endl;
491 
492   do
493   {
494     internal::arpack_wrapper<Scalar, RealScalar>::saupd(&ido, bmat, &n, whch, &nev, &tol, resid,
495                                                         &ncv, v, &ldv, iparam, ipntr, workd, workl,
496                                                         &lworkl, &info);
497 
498     if (ido == -1 || ido == 1)
499     {
500       Scalar *in  = workd + ipntr[0] - 1;
501       Scalar *out = workd + ipntr[1] - 1;
502 
503       if (ido == 1 && mode != 2)
504       {
505           Scalar *out2 = workd + ipntr[2] - 1;
506           if (isBempty || mode == 1)
507             Matrix<Scalar, Dynamic, 1>::Map(out2, n) = Matrix<Scalar, Dynamic, 1>::Map(in, n);
508           else
509             Matrix<Scalar, Dynamic, 1>::Map(out2, n) = B * Matrix<Scalar, Dynamic, 1>::Map(in, n);
510 
511           in = workd + ipntr[2] - 1;
512       }
513 
514       if (mode == 1)
515       {
516         if (isBempty)
517         {
518           // OP = A
519           //
520           Matrix<Scalar, Dynamic, 1>::Map(out, n) = A * Matrix<Scalar, Dynamic, 1>::Map(in, n);
521         }
522         else
523         {
524           // OP = L^{-1}AL^{-T}
525           //
526           internal::OP<MatrixSolver, MatrixType, Scalar, BisSPD>::applyOP(OP, A, n, in, out);
527         }
528       }
529       else if (mode == 2)
530       {
531         if (ido == 1)
532           Matrix<Scalar, Dynamic, 1>::Map(in, n)  = A * Matrix<Scalar, Dynamic, 1>::Map(in, n);
533 
534         // OP = B^{-1} A
535         //
536         Matrix<Scalar, Dynamic, 1>::Map(out, n) = OP.solve(Matrix<Scalar, Dynamic, 1>::Map(in, n));
537       }
538       else if (mode == 3)
539       {
540         // OP = (A-\sigmaB)B (\sigma could be 0, and B could be I)
541         // The B * in is already computed and stored at in if ido == 1
542         //
543         if (ido == 1 || isBempty)
544           Matrix<Scalar, Dynamic, 1>::Map(out, n) = OP.solve(Matrix<Scalar, Dynamic, 1>::Map(in, n));
545         else
546           Matrix<Scalar, Dynamic, 1>::Map(out, n) = OP.solve(B * Matrix<Scalar, Dynamic, 1>::Map(in, n));
547       }
548     }
549     else if (ido == 2)
550     {
551       Scalar *in  = workd + ipntr[0] - 1;
552       Scalar *out = workd + ipntr[1] - 1;
553 
554       if (isBempty || mode == 1)
555         Matrix<Scalar, Dynamic, 1>::Map(out, n) = Matrix<Scalar, Dynamic, 1>::Map(in, n);
556       else
557         Matrix<Scalar, Dynamic, 1>::Map(out, n) = B * Matrix<Scalar, Dynamic, 1>::Map(in, n);
558     }
559   } while (ido != 99);
560 
561   if (info == 1)
562     m_info = NoConvergence;
563   else if (info == 3)
564     m_info = NumericalIssue;
565   else if (info < 0)
566     m_info = InvalidInput;
567   else if (info != 0)
568     eigen_assert(false && "Unknown ARPACK return value!");
569   else
570   {
571     // Do we compute eigenvectors or not?
572     //
573     int rvec = (options & ComputeEigenvectors) == ComputeEigenvectors;
574 
575     // "A" means "All", use "S" to choose specific eigenvalues (not yet supported in ARPACK))
576     //
577     char howmny[2] = "A";
578 
579     // if howmny == "S", specifies the eigenvalues to compute (not implemented in ARPACK)
580     //
581     int *select = new int[ncv];
582 
583     // Final eigenvalues
584     //
585     m_eivalues.resize(nev, 1);
586 
587     internal::arpack_wrapper<Scalar, RealScalar>::seupd(&rvec, howmny, select, m_eivalues.data(), v, &ldv,
588                                                         &sigma, bmat, &n, whch, &nev, &tol, resid, &ncv,
589                                                         v, &ldv, iparam, ipntr, workd, workl, &lworkl, &info);
590 
591     if (info == -14)
592       m_info = NoConvergence;
593     else if (info != 0)
594       m_info = InvalidInput;
595     else
596     {
597       if (rvec)
598       {
599         m_eivec.resize(A.rows(), nev);
600         for (int i=0; i<nev; i++)
601           for (int j=0; j<n; j++)
602             m_eivec(j,i) = v[i*n+j] / scale;
603 
604         if (mode == 1 && !isBempty && BisSPD)
605           internal::OP<MatrixSolver, MatrixType, Scalar, BisSPD>::project(OP, n, nev, m_eivec.data());
606 
607         m_eigenvectorsOk = true;
608       }
609 
610       m_nbrIterations = iparam[2];
611       m_nbrConverged  = iparam[4];
612 
613       m_info = Success;
614     }
615 
616     delete[] select;
617   }
618 
619   delete[] v;
620   delete[] iparam;
621   delete[] ipntr;
622   delete[] workd;
623   delete[] workl;
624   delete[] resid;
625 
626   m_isInitialized = true;
627 
628   return *this;
629 }
630 
631 
632 // Single precision
633 //
634 extern "C" void ssaupd_(int *ido, char *bmat, int *n, char *which,
635     int *nev, float *tol, float *resid, int *ncv,
636     float *v, int *ldv, int *iparam, int *ipntr,
637     float *workd, float *workl, int *lworkl,
638     int *info);
639 
640 extern "C" void sseupd_(int *rvec, char *All, int *select, float *d,
641     float *z, int *ldz, float *sigma,
642     char *bmat, int *n, char *which, int *nev,
643     float *tol, float *resid, int *ncv, float *v,
644     int *ldv, int *iparam, int *ipntr, float *workd,
645     float *workl, int *lworkl, int *ierr);
646 
647 // Double precision
648 //
649 extern "C" void dsaupd_(int *ido, char *bmat, int *n, char *which,
650     int *nev, double *tol, double *resid, int *ncv,
651     double *v, int *ldv, int *iparam, int *ipntr,
652     double *workd, double *workl, int *lworkl,
653     int *info);
654 
655 extern "C" void dseupd_(int *rvec, char *All, int *select, double *d,
656     double *z, int *ldz, double *sigma,
657     char *bmat, int *n, char *which, int *nev,
658     double *tol, double *resid, int *ncv, double *v,
659     int *ldv, int *iparam, int *ipntr, double *workd,
660     double *workl, int *lworkl, int *ierr);
661 
662 
663 namespace internal {
664 
665 template<typename Scalar, typename RealScalar> struct arpack_wrapper
666 {
saupdarpack_wrapper667   static inline void saupd(int *ido, char *bmat, int *n, char *which,
668       int *nev, RealScalar *tol, Scalar *resid, int *ncv,
669       Scalar *v, int *ldv, int *iparam, int *ipntr,
670       Scalar *workd, Scalar *workl, int *lworkl, int *info)
671   {
672     EIGEN_STATIC_ASSERT(!NumTraits<Scalar>::IsComplex, NUMERIC_TYPE_MUST_BE_REAL)
673   }
674 
seupdarpack_wrapper675   static inline void seupd(int *rvec, char *All, int *select, Scalar *d,
676       Scalar *z, int *ldz, RealScalar *sigma,
677       char *bmat, int *n, char *which, int *nev,
678       RealScalar *tol, Scalar *resid, int *ncv, Scalar *v,
679       int *ldv, int *iparam, int *ipntr, Scalar *workd,
680       Scalar *workl, int *lworkl, int *ierr)
681   {
682     EIGEN_STATIC_ASSERT(!NumTraits<Scalar>::IsComplex, NUMERIC_TYPE_MUST_BE_REAL)
683   }
684 };
685 
686 template <> struct arpack_wrapper<float, float>
687 {
688   static inline void saupd(int *ido, char *bmat, int *n, char *which,
689       int *nev, float *tol, float *resid, int *ncv,
690       float *v, int *ldv, int *iparam, int *ipntr,
691       float *workd, float *workl, int *lworkl, int *info)
692   {
693     ssaupd_(ido, bmat, n, which, nev, tol, resid, ncv, v, ldv, iparam, ipntr, workd, workl, lworkl, info);
694   }
695 
696   static inline void seupd(int *rvec, char *All, int *select, float *d,
697       float *z, int *ldz, float *sigma,
698       char *bmat, int *n, char *which, int *nev,
699       float *tol, float *resid, int *ncv, float *v,
700       int *ldv, int *iparam, int *ipntr, float *workd,
701       float *workl, int *lworkl, int *ierr)
702   {
703     sseupd_(rvec, All, select, d, z, ldz, sigma, bmat, n, which, nev, tol, resid, ncv, v, ldv, iparam, ipntr,
704         workd, workl, lworkl, ierr);
705   }
706 };
707 
708 template <> struct arpack_wrapper<double, double>
709 {
710   static inline void saupd(int *ido, char *bmat, int *n, char *which,
711       int *nev, double *tol, double *resid, int *ncv,
712       double *v, int *ldv, int *iparam, int *ipntr,
713       double *workd, double *workl, int *lworkl, int *info)
714   {
715     dsaupd_(ido, bmat, n, which, nev, tol, resid, ncv, v, ldv, iparam, ipntr, workd, workl, lworkl, info);
716   }
717 
718   static inline void seupd(int *rvec, char *All, int *select, double *d,
719       double *z, int *ldz, double *sigma,
720       char *bmat, int *n, char *which, int *nev,
721       double *tol, double *resid, int *ncv, double *v,
722       int *ldv, int *iparam, int *ipntr, double *workd,
723       double *workl, int *lworkl, int *ierr)
724   {
725     dseupd_(rvec, All, select, d, v, ldv, sigma, bmat, n, which, nev, tol, resid, ncv, v, ldv, iparam, ipntr,
726         workd, workl, lworkl, ierr);
727   }
728 };
729 
730 
731 template<typename MatrixSolver, typename MatrixType, typename Scalar, bool BisSPD>
732 struct OP
733 {
734     static inline void applyOP(MatrixSolver &OP, const MatrixType &A, int n, Scalar *in, Scalar *out);
735     static inline void project(MatrixSolver &OP, int n, int k, Scalar *vecs);
736 };
737 
738 template<typename MatrixSolver, typename MatrixType, typename Scalar>
739 struct OP<MatrixSolver, MatrixType, Scalar, true>
740 {
741   static inline void applyOP(MatrixSolver &OP, const MatrixType &A, int n, Scalar *in, Scalar *out)
742 {
743     // OP = L^{-1} A L^{-T}  (B = LL^T)
744     //
745     // First solve L^T out = in
746     //
747     Matrix<Scalar, Dynamic, 1>::Map(out, n) = OP.matrixU().solve(Matrix<Scalar, Dynamic, 1>::Map(in, n));
748     Matrix<Scalar, Dynamic, 1>::Map(out, n) = OP.permutationPinv() * Matrix<Scalar, Dynamic, 1>::Map(out, n);
749 
750     // Then compute out = A out
751     //
752     Matrix<Scalar, Dynamic, 1>::Map(out, n) = A * Matrix<Scalar, Dynamic, 1>::Map(out, n);
753 
754     // Then solve L out = out
755     //
756     Matrix<Scalar, Dynamic, 1>::Map(out, n) = OP.permutationP() * Matrix<Scalar, Dynamic, 1>::Map(out, n);
757     Matrix<Scalar, Dynamic, 1>::Map(out, n) = OP.matrixL().solve(Matrix<Scalar, Dynamic, 1>::Map(out, n));
758 }
759 
760   static inline void project(MatrixSolver &OP, int n, int k, Scalar *vecs)
761 {
762     // Solve L^T out = in
763     //
764     Matrix<Scalar, Dynamic, Dynamic>::Map(vecs, n, k) = OP.matrixU().solve(Matrix<Scalar, Dynamic, Dynamic>::Map(vecs, n, k));
765     Matrix<Scalar, Dynamic, Dynamic>::Map(vecs, n, k) = OP.permutationPinv() * Matrix<Scalar, Dynamic, Dynamic>::Map(vecs, n, k);
766 }
767 
768 };
769 
770 template<typename MatrixSolver, typename MatrixType, typename Scalar>
771 struct OP<MatrixSolver, MatrixType, Scalar, false>
772 {
773   static inline void applyOP(MatrixSolver &OP, const MatrixType &A, int n, Scalar *in, Scalar *out)
774 {
775     eigen_assert(false && "Should never be in here...");
776 }
777 
778   static inline void project(MatrixSolver &OP, int n, int k, Scalar *vecs)
779 {
780     eigen_assert(false && "Should never be in here...");
781 }
782 
783 };
784 
785 } // end namespace internal
786 
787 } // end namespace Eigen
788 
789 #endif // EIGEN_ARPACKSELFADJOINTEIGENSOLVER_H
790 
791