Fix MSVC warning.

Eigen/src/Core/MathFunctions.h

diff --git a/Eigen/src/Core/MathFunctions.h b/Eigen/src/Core/MathFunctions.h
index e47070a..e87b60f 100644
--- a/Eigen/src/Core/MathFunctions.h
+++ b/Eigen/src/Core/MathFunctions.h
@@ -748,9 +748,9 @@
 }
 
 //MSVC defines a _isnan builtin function, but for double only
-EIGEN_DEVICE_FUNC inline bool isnan_impl(const long double& x) { return _isnan(x); }
-EIGEN_DEVICE_FUNC inline bool isnan_impl(const double& x)      { return _isnan(x); }
-EIGEN_DEVICE_FUNC inline bool isnan_impl(const float& x)       { return _isnan(x); }
+EIGEN_DEVICE_FUNC inline bool isnan_impl(const long double& x) { return _isnan(x)!=0; }
+EIGEN_DEVICE_FUNC inline bool isnan_impl(const double& x)      { return _isnan(x)!=0; }
+EIGEN_DEVICE_FUNC inline bool isnan_impl(const float& x)       { return _isnan(x)!=0; }
 
 EIGEN_DEVICE_FUNC inline bool isinf_impl(const long double& x) { return isinf_msvc_helper(x); }
 EIGEN_DEVICE_FUNC inline bool isinf_impl(const double& x)      { return isinf_msvc_helper(x); }