diff --git a/lib/classifier-reborn/extensions/vector.rb b/lib/classifier-reborn/extensions/vector.rb
index 1b0594d..17ed760 100644
--- a/lib/classifier-reborn/extensions/vector.rb
+++ b/lib/classifier-reborn/extensions/vector.rb
@@ -61,7 +61,7 @@ def SV_decomp(maxSweeps = 20)
     end # of do while true
     s = []
     qrot.row_size.times do |r|
-      s << Math.sqrt(qrot[r, r])
+      s << Math.sqrt(qrot[r, r] + 1e-7)
     end
     # puts "cnt = #{cnt}"
     if row_size >= column_size