Determine whether a floating-point number is negative
Synopsis:
#include <math.h>
#define signbit( x ) ...
Arguments:
- x
- A floating-point value.
Library:
- libm
- The general-purpose math library.
- libm-sve
- (QNX Neutrino 7.1 or later)
A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.
Your system requirements will determine how you should work with these libraries:
- If you want only selected processes to run with the SVE version, you can include both libraries in your OS image
and use the -l m or -l m-sve option to
qcc
to link explicitly against the appropriate one.
- If you want all processes to use the SVE version, include libm-sve.so in your OS image
and set up a symbolic link from libm.so to libm-sve.so.
Use the -l m option to
qcc
to link against the library.
Note:
Compile your program with the -fno-builtin option to prevent the compiler from using a
built-in version of the function.
Description:
The signbit() macro determines whether the given floating-point number is negative.
The sign bit is set for negative numbers, including negative NaN, negative zero, and negative infinity.
Returns:
Nonzero if the given number is negative.
Classification:
C11,
POSIX 1003.1
| Safety: |
|
|---|
| Cancellation point |
No |
| Interrupt handler |
Yes |
| Signal handler |
Yes |
| Thread |
Yes |