Clarify isNonnegative() behavior in comments

Also fix some comments of isNaN() and isPositive() functions.
No code changes.

1 files changed, 5 insertions, 4 deletions

diff --git a/Macros.h b/Macros.h
index 01cc7774..051bedbc 100644
--- a/Macros.h
+++ b/Macros.h
@@ -119,19 +119,20 @@ in the source distribution for its full text.
 #endif
 
 /* Cheaper function for checking NaNs. Unlike the standard isnan(), this may
-   throw an FP exception on a "signaling" NaN.
+   throw an FP exception on a "signaling NaN".
    (ISO/IEC TS 18661-1 and the C23 standard stated that isnan() throws no
-   exceptions even with a "signaling" NaN) */
+   exceptions even with a "signaling NaN") */
 static inline bool isNaN(double x) {
    return !isgreaterequal(x, x);
 }
 
-/* Checks if x is nonnegative. Returns false if x is NaN. */
+/* Checks if x >= 0.0 but returns false if x is NaN. Because IEEE 754 considers
+   -0.0 == 0.0, this function treats both zeros as nonnegative. */
 static inline bool isNonnegative(double x) {
    return isgreaterequal(x, 0.0);
 }
 
-/* Checks if x is positive. Returns false if x is NaN. */
+/* Checks if x > 0.0 but returns false if x is NaN. */
 static inline bool isPositive(double x) {
    return isgreater(x, 0.0);
 }