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 "common.h"
11 #include <Eigen/Eigenvalues>
12 
13 // computes an LU factorization of a general M-by-N matrix A using partial pivoting with row interchanges
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 nb = ILAENV( 1, 'SSYTRD', UPLO, N, -1, -1, -1 )
29 //          LWKOPT = MAX( 1, ( NB+2 )*N )
30 //          WORK( 1 ) = LWKOPT
31 // *
32 //          IF( LWORK.LT.MAX( 1, 3*N-1 ) .AND. .NOT.LQUERY )
33 //      $      INFO = -8
34 //       END IF
35 // *
36 //       IF( INFO.NE.0 ) THEN
37 //          CALL XERBLA( 'SSYEV ', -INFO )
38 //          RETURN
39 //       ELSE IF( LQUERY ) THEN
40 //          RETURN
41 //       END IF
42 
43   if(*info!=0)
44   {
45     int e = -*info;
46     return xerbla_(SCALAR_SUFFIX_UP"SYEV ", &e, 6);
47   }
48 
49   if(query_size)
50   {
51     *lwork = 0;
52     return 0;
53   }
54 
55   if(*n==0)
56     return 0;
57 
58   PlainMatrixType mat(*n,*n);
59   if(UPLO(*uplo)==UP) mat = matrix(a,*n,*n,*lda).adjoint();
60   else                mat = matrix(a,*n,*n,*lda);
61 
62   bool computeVectors = *jobz=='V' || *jobz=='v';
63   SelfAdjointEigenSolver<PlainMatrixType> eig(mat,computeVectors?ComputeEigenvectors:EigenvaluesOnly);
64 
65   if(eig.info()==NoConvergence)
66   {
67     vector(w,*n).setZero();
68     if(computeVectors)
69       matrix(a,*n,*n,*lda).setIdentity();
70     //*info = 1;
71     return 0;
72   }
73 
74   vector(w,*n) = eig.eigenvalues();
75   if(computeVectors)
76     matrix(a,*n,*n,*lda) = eig.eigenvectors();
77 
78   return 0;
79 }
80