Enable and fix -Wdouble-conversion warnings
diff --git a/test/sparse_basic.cpp b/test/sparse_basic.cpp
index cb8ebae..aa38825 100644
--- a/test/sparse_basic.cpp
+++ b/test/sparse_basic.cpp
@@ -232,11 +232,11 @@
       for (Index i=0; i<m2.rows(); ++i)
       {
         float x = internal::random<float>(0,1);
-        if (x<0.1)
+        if (x<0.1f)
         {
           // do nothing
         }
-        else if (x<0.5)
+        else if (x<0.5f)
         {
           countFalseNonZero++;
           m2.insert(i,j) = Scalar(0);