1 files changed, 42 insertions, 0 deletions
diff --git a/utils/nan.h b/utils/nan.h
new file mode 100755
index 00000000..257364d5
--- /dev/null
+++ b/utils/nan.h
@@ -0,0 +1,42 @@
+#ifndef NAN_H
+#define NAN_H
+//TODO: switch to C99 isnan isfinite isinf etc. (faster)
+
+#include <limits>
+
+template <bool> struct nan_static_assert;
+template <> struct nan_static_assert<true> { };
+
+// is_iec559 i.e. only IEEE 754 float has x != x <=> x is nan
+template<typename T>
+inline bool is_nan(T x) {
+//    static_cast<void>(sizeof(nan_static_assert<std::numeric_limits<T>::has_quiet_NaN>));
+    return std::numeric_limits<T>::has_quiet_NaN && (x != x);
+}
+
+template <typename T>
+inline bool is_inf(T x) {
+//    static_cast<void>(sizeof(nan_static_assert<std::numeric_limits<T>::has_infinity>));
+    return x == std::numeric_limits<T>::infinity() || x == -std::numeric_limits<T>::infinity();
+}
+
+template <typename T>
+inline bool is_pos_inf(T x) {
+//    static_cast<void>(sizeof(nan_static_assert<std::numeric_limits<T>::has_infinity>));
+    return x == std::numeric_limits<T>::infinity();
+}
+
+template <typename T>
+inline bool is_neg_inf(T x) {
+//    static_cast<void>(sizeof(nan_static_assert<std::numeric_limits<T>::has_infinity>));
+    return x == -std::numeric_limits<T>::infinity();
+}
+
+//c99 isfinite macro shoudl be much faster
+template <typename T>
+inline bool is_finite(T x) {
+  return !is_nan(x) && !is_inf(x);
+}
+
+
+#endif