#include <math.h>
double fabs(double x);
float fabsf(float x);
long double fabsl(long double x);
The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to the ISO C standard.
These functions shall compute the absolute value of their argument x,| x|.
Upon successful completion, these functions shall return the absolute value of x.
If x is NaN, a NaN shall be returned.
If x is ±0, +0 shall be returned.
If x is ±Inf, +Inf shall be returned.
No errors are defined.
The following sections are informative.
None.
None.
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isnan() , the Base Definitions volume of IEEE Std 1003.1-2001, <math.h>