fdim(3) Library Functions Manual fdim(3)

fdim, fdimf, fdiml - positive difference

Math library (libm, -lm)

#include <math.h>
double fdim(double x, double y);
float fdimf(float x, float y);
long double fdiml(long double x, long double y);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

fdimf(), fdiml():

    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

These functions return the positive difference, max(x-y,0), between their arguments.

On success, these functions return the positive difference.

If x or y is a NaN, a NaN is returned.

If the result overflows, a range error occurs, and the functions return HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively.

See math_error(7) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:

errno is set to ERANGE. An overflow floating-point exception (FE_OVERFLOW) is raised.

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
fdim (), fdimf (), fdiml () Thread safety MT-Safe

C11, POSIX.1-2008.

glibc 2.1. C99, POSIX.1-2001.

Before glibc 2.24 on certain architectures (e.g., x86, but not x86_64) these functions did not set errno.


2024-05-02 Linux man-pages 6.8