isnormal()

Updated: October 26, 2022

Determine whether a floating-point number is normal

Synopsis:

#include <math.h>

#define isnormal( 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:

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.

Description:

The isnormal() macro determines whether the given floating-point number is normal (i.e., neither zero, subnormal, infinite, nor NaN).

Returns:

Nonzero
The value of x is normal.
0
The value of x isn't normal.

Classification:

C11, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes