From 53026d29d41e81065b28631445e8eb5c4044c187 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Tue, 31 Jan 2017 14:22:42 +0100
Subject: bug #478: fix regression in the eigen decomposition of zero matrices.

---
 test/eigensolver_selfadjoint.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'test/eigensolver_selfadjoint.cpp')

diff --git a/test/eigensolver_selfadjoint.cpp b/test/eigensolver_selfadjoint.cpp
index 4ed126116..39ad4130e 100644
--- a/test/eigensolver_selfadjoint.cpp
+++ b/test/eigensolver_selfadjoint.cpp
@@ -180,6 +180,15 @@ template<typename MatrixType> void selfadjointeigensolver(const MatrixType& m)
     SelfAdjointEigenSolver<MatrixType> eig(a.adjoint() * a);
     eig.compute(a.adjoint() * a);
   }
+
+  // regression test for bug 478
+  {
+    a.setZero();
+    SelfAdjointEigenSolver<MatrixType> ei3(a);
+    VERIFY_IS_EQUAL(ei3.info(), Success);
+    VERIFY_IS_MUCH_SMALLER_THAN(ei3.eigenvalues().norm(),RealScalar(1));
+    VERIFY((ei3.eigenvectors().transpose()*ei3.eigenvectors().transpose()).eval().isIdentity());
+  }
 }
 
 template<int>
-- 
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