From e66caf48e871f4c63460d6632605e055bde14156 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Tue, 12 May 2015 18:44:46 +0200
Subject: [PATCH] Make test matrices for eigensolver/selfadjoint even more
 tricky

---
 test/svd_fill.h | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/test/svd_fill.h b/test/svd_fill.h
index aa75326d9..7e44b3d05 100644
--- a/test/svd_fill.h
+++ b/test/svd_fill.h
@@ -53,19 +53,35 @@ void svd_fill_random(MatrixType &m, int Option = 0)
     VT.setRandom();
   }
   
+  Matrix<Scalar,Dynamic,1> samples(7);
+  samples << 0, 5.60844e-313, -5.60844e-313, 4.94e-324, -4.94e-324, -1./NumTraits<RealScalar>::highest(), 1./NumTraits<RealScalar>::highest();
+  
   if(Option==Symmetric)
   {
     m = U * d.asDiagonal() * U.transpose();
     
     // randomly nullify some rows/columns
     {
-      Index count = internal::random<Index>(-1,1);
+      Index count = internal::random<Index>(-diagSize,diagSize);
       for(Index k=0; k<count; ++k)
       {
         Index i = internal::random<Index>(0,diagSize-1);
         m.row(i).setZero();
         m.col(i).setZero();
       }
+      if(count<0)
+      // (partly) cancel some coeffs
+      if(!(dup && unit_uv))
+      {
+        
+        Index n = internal::random<Index>(0,m.size()-1);
+        for(Index k=0; k<n; ++k)
+        {
+          Index i = internal::random<Index>(0,m.rows()-1);
+          Index j = internal::random<Index>(0,m.cols()-1);
+          m(j,i) = m(i,j) = samples(internal::random<Index>(0,samples.size()-1));
+        }
+      }
     }
   }
   else
@@ -74,11 +90,9 @@ void svd_fill_random(MatrixType &m, int Option = 0)
     // (partly) cancel some coeffs
     if(!(dup && unit_uv))
     {
-      Matrix<Scalar,Dynamic,1> samples(7);
-      samples << 0, 5.60844e-313, -5.60844e-313, 4.94e-324, -4.94e-324, -1./NumTraits<RealScalar>::highest(), 1./NumTraits<RealScalar>::highest();
       Index n = internal::random<Index>(0,m.size()-1);
       for(Index i=0; i<n; ++i)
-        m(internal::random<Index>(0,m.rows()-1), internal::random<Index>(0,m.cols()-1)) = samples(internal::random<Index>(0,6));
+        m(internal::random<Index>(0,m.rows()-1), internal::random<Index>(0,m.cols()-1)) = samples(internal::random<Index>(0,samples.size()-1));
     }
   }
 }