double fabs(double x);
float fabsf(float x);
long double fabsl(long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
These functions return the absolute value of the floating-point number
These functions return the absolute value of x.
If x is a NaN, a NaN is returned.
If x is -0, +0 is returned.
If x is negative infinity or positive infinity, positive infinity is
No errors occur.
Multithreading (see pthreads(7))
The fabs(), fabsf(), and fabsl() functions are thread-safe.
C99, POSIX.1-2001. The variant returning double also conforms to SVr4,
abs(3), cabs(3), ceil(3), floor(3), labs(3), rint(3)
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