1 // This file is part of Eigen, a lightweight C++ template library
2 // for linear algebra.
3 //
4 // Copyright (C) 2011 Gael Guennebaud <gael.guennebaud@inria.fr>
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 #include "lapack_common.h"
11 #include <Eigen/Eigenvalues>
12 
13 // computes eigen values and vectors of a general N-by-N matrix A
14 EIGEN_LAPACK_FUNC(syev,(char *jobz, char *uplo, int* n, Scalar* a, int *lda, Scalar* w, Scalar* /*work*/, int* lwork, int *info))
15 {
16   // TODO exploit the work buffer
17   bool query_size = *lwork==-1;
18 
19   *info = 0;
20         if(*jobz!='N' && *jobz!='V')                    *info = -1;
21   else  if(UPLO(*uplo)==INVALID)                        *info = -2;
22   else  if(*n<0)                                        *info = -3;
23   else  if(*lda<std::max(1,*n))                         *info = -5;
24   else  if((!query_size) && *lwork<std::max(1,3**n-1))  *info = -8;
25 
26   if(*info!=0)
27   {
28     int e = -*info;
29     return xerbla_(SCALAR_SUFFIX_UP"SYEV ", &e, 6);
30   }
31 
32   if(query_size)
33   {
34     *lwork = 0;
35     return 0;
36   }
37 
38   if(*n==0)
39     return 0;
40 
41   PlainMatrixType mat(*n,*n);
42   if(UPLO(*uplo)==UP) mat = matrix(a,*n,*n,*lda).adjoint();
43   else                mat = matrix(a,*n,*n,*lda);
44 
45   bool computeVectors = *jobz=='V' || *jobz=='v';
46   SelfAdjointEigenSolver<PlainMatrixType> eig(mat,computeVectors?ComputeEigenvectors:EigenvaluesOnly);
47 
48   if(eig.info()==NoConvergence)
49   {
50     make_vector(w,*n).setZero();
51     if(computeVectors)
52       matrix(a,*n,*n,*lda).setIdentity();
53     //*info = 1;
54     return 0;
55   }
56 
57   make_vector(w,*n) = eig.eigenvalues();
58   if(computeVectors)
59     matrix(a,*n,*n,*lda) = eig.eigenvectors();
60 
61   return 0;
62 }
63