Fix bug #894: the sign of LDLT was not re-initialized at each call of compute()

2 files changed, 8 insertions, 5 deletions

diff --git a/Eigen/src/Cholesky/LDLT.h b/Eigen/src/Cholesky/LDLT.h
index b4016cd6c..dfc473df1 100644
--- a/Eigen/src/Cholesky/LDLT.h
+++ b/Eigen/src/Cholesky/LDLT.h
@@ -433,6 +433,7 @@ LDLT<MatrixType,_UpLo>& LDLT<MatrixType,_UpLo>::compute(const MatrixType& a)
   m_transpositions.resize(size);
   m_isInitialized = false;
   m_temporary.resize(size);
+  m_sign = internal::ZeroSign;
 
   internal::ldlt_inplace<UpLo>::unblocked(m_matrix, m_transpositions, m_temporary, m_sign);
 
diff --git a/test/cholesky.cpp b/test/cholesky.cpp
index a883192ab..33e32a322 100644
--- a/test/cholesky.cpp
+++ b/test/cholesky.cpp
@@ -316,33 +316,35 @@ template<typename MatrixType> void cholesky_definiteness(const MatrixType& m)
 {
   eigen_assert(m.rows() == 2 && m.cols() == 2);
   MatrixType mat;
+  LDLT<MatrixType> ldlt(2);
+  
   {
     mat << 1, 0, 0, -1;
-    LDLT<MatrixType> ldlt(mat);
+    ldlt.compute(mat);
     VERIFY(!ldlt.isNegative());
     VERIFY(!ldlt.isPositive());
   }
   {
     mat << 1, 2, 2, 1;
-    LDLT<MatrixType> ldlt(mat);
+    ldlt.compute(mat);
     VERIFY(!ldlt.isNegative());
     VERIFY(!ldlt.isPositive());
   }
   {
     mat << 0, 0, 0, 0;
-    LDLT<MatrixType> ldlt(mat);
+    ldlt.compute(mat);
     VERIFY(ldlt.isNegative());
     VERIFY(ldlt.isPositive());
   }
   {
     mat << 0, 0, 0, 1;
-    LDLT<MatrixType> ldlt(mat);
+    ldlt.compute(mat);
     VERIFY(!ldlt.isNegative());
     VERIFY(ldlt.isPositive());
   }
   {
     mat << -1, 0, 0, 0;
-    LDLT<MatrixType> ldlt(mat);
+    ldlt.compute(mat);
     VERIFY(ldlt.isNegative());
     VERIFY(!ldlt.isPositive());
   }