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+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2011 Gael Guennebaud <gael.guennebaud@inria.fr>
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include "lapack_common.h"
+#include <Eigen/Eigenvalues>
+
+// computes eigen values and vectors of a general N-by-N matrix A
+EIGEN_LAPACK_FUNC(syev)
+(char* jobz, char* uplo, int* n, Scalar* a, int* lda, Scalar* w, Scalar* /*work*/, int* lwork, int* info) {
+  // TODO exploit the work buffer
+  bool query_size = *lwork == -1;
+
+  *info = 0;
+  if (*jobz != 'N' && *jobz != 'V')
+    *info = -1;
+  else if (UPLO(*uplo) == INVALID)
+    *info = -2;
+  else if (*n < 0)
+    *info = -3;
+  else if (*lda < std::max(1, *n))
+    *info = -5;
+  else if ((!query_size) && *lwork < std::max(1, 3 * *n - 1))
+    *info = -8;
+
+  if (*info != 0) {
+    int e = -*info;
+    return xerbla_(SCALAR_SUFFIX_UP "SYEV ", &e);
+  }
+
+  if (query_size) {
+    *lwork = 0;
+    return;
+  }
+
+  if (*n == 0) return;
+
+  PlainMatrixType mat(*n, *n);
+  if (UPLO(*uplo) == UP)
+    mat = matrix(a, *n, *n, *lda).adjoint();
+  else
+    mat = matrix(a, *n, *n, *lda);
+
+  bool computeVectors = *jobz == 'V' || *jobz == 'v';
+  Eigen::SelfAdjointEigenSolver<PlainMatrixType> eig(
+      mat, computeVectors ? Eigen::ComputeEigenvectors : Eigen::EigenvaluesOnly);
+
+  if (eig.info() == Eigen::NoConvergence) {
+    make_vector(w, *n).setZero();
+    if (computeVectors) matrix(a, *n, *n, *lda).setIdentity();
+    //*info = 1;
+    return;
+  }
+
+  make_vector(w, *n) = eig.eigenvalues();
+  if (computeVectors) matrix(a, *n, *n, *lda) = eig.eigenvectors();
+}