diff --git a/libraries/AP_Math/AP_Math.h b/libraries/AP_Math/AP_Math.h
index dad56acd3f..1580c5228d 100644
--- a/libraries/AP_Math/AP_Math.h
+++ b/libraries/AP_Math/AP_Math.h
@@ -78,6 +78,27 @@ inline bool is_negative(const T fVal1) {
 }
 
 
+/*
+ * @brief: Check whether a double is zero
+ */
+inline bool is_zero(const double fVal1) {
+    return (fabsf(fVal1) < static_cast<double>(FLT_EPSILON));
+}
+
+/*
+ * @brief: Check whether a double is greater than zero
+ */
+inline bool is_positive(const double fVal1) {
+    return (fVal1 >= static_cast<double>(FLT_EPSILON));
+}
+
+/*
+ * @brief: Check whether a double is less than zero
+ */
+inline bool is_negative(const double fVal1) {
+    return (fVal1 <= static_cast<double>((-1.0 * FLT_EPSILON)));
+}
+
 /*
  * A variant of asin() that checks the input ranges and ensures a valid angle
  * as output. If nan is given as input then zero is returned.