fix readcost for complex types

Eigen/src/Core/NumTraits.h

diff --git a/Eigen/src/Core/NumTraits.h b/Eigen/src/Core/NumTraits.h
index 76bf8a5..70ea7ef 100644
--- a/Eigen/src/Core/NumTraits.h
+++ b/Eigen/src/Core/NumTraits.h
@@ -113,7 +113,7 @@
   typedef _Real Real;
   enum {
     IsComplex = 1,
-    ReadCost = 2,
+    ReadCost = 2 * NumTraits<_Real>::ReadCost,
     AddCost = 2 * NumTraits<Real>::AddCost,
     MulCost = 4 * NumTraits<Real>::MulCost + 2 * NumTraits<Real>::AddCost
   };