fdim(3) — Linux manual page

fdim(3)                  Library Functions Manual                 fdim(3)

NAME         top

       fdim, fdimf, fdiml - positive difference

LIBRARY         top

       Math library (libm, -lm)

SYNOPSIS         top

       #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

DESCRIPTION         top

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

RETURN VALUE         top

       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.

ERRORS         top

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

       The following errors can occur:

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

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                            │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │ fdim(), fdimf(), fdiml()             │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS         top

       C11, POSIX.1-2008.

HISTORY         top

       glibc 2.1.  C99, POSIX.1-2001.

BUGS         top

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

SEE ALSO         top

       fmax(3)

COLOPHON         top

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Linux man-pages 6.15            2025-05-17                        fdim(3)

Pages that refer to this page: fmax(3),  fmin(3)

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