make casts explicit and fixed the type

test/rand.cpp

diff --git a/test/rand.cpp b/test/rand.cpp
index b4cc179..4d686bf 100644
--- a/test/rand.cpp
+++ b/test/rand.cpp
@@ -57,8 +57,9 @@
 EIGEN_DECLARE_TEST(rand)
 {
   long long_ref = NumTraits<long>::highest()/10;
-  signed char char_offset = (std::min)(g_repeat,64);
-  signed char short_offset = (std::min)(g_repeat,16000);
+  // the minimum guarantees that these conversions are safe
+  auto char_offset = static_cast<signed char>((std::min)(g_repeat, 64));
+  auto short_offset = static_cast<signed short>((std::min)(g_repeat, 8000));
 
   for(int i = 0; i < g_repeat*10000; i++) {
     CALL_SUBTEST(check_in_range<float>(10,11));