fabs(3) Library Functions Manual fabs(3) NAME fabs, fabsf, fabsl - absolute value of floating-point number LIBRARY Math library (libm, -lm) SYNOPSIS #include double fabs(double x); float fabsf(float x); long double fabsl(long double x); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): fabsf(), fabsl(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE DESCRIPTION These functions return the absolute value of the floating-point number x. RETURN VALUE 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 returned. ERRORS No errors occur. ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). +--------------------------------------------+---------------+---------+ |Interface | Attribute | Value | +--------------------------------------------+---------------+---------+ |fabs (), fabsf (), fabsl () | Thread safety | MT-Safe | +--------------------------------------------+---------------+---------+ STANDARDS C11, POSIX.1-2008. HISTORY C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD, C89. SEE ALSO abs(3), cabs(3), ceil(3), floor(3), labs(3), rint(3) Linux man-pages 6.9.1 2024-05-02 fabs(3)