remainder(3) — Linux manual page

remainder(3)            Library Functions Manual            remainder(3)

NAME

       drem, dremf, dreml, remainder, remainderf, remainderl - floating-
       point remainder function

LIBRARY

       Math library (libm, -lm)

SYNOPSIS

       #include <math.h>

       double remainder(double x, double y);
       float remainderf(float x, float y);
       long double remainderl(long double x, long double y);

       /* Obsolete synonyms */
       [[deprecated]] double drem(double x, double y);
       [[deprecated]] float dremf(float x, float y);
       [[deprecated]] long double dreml(long double x, long double y);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       remainder():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || _XOPEN_SOURCE >= 500
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

       remainderf(), remainderl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

       drem(), dremf(), dreml():
           /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       These functions compute the remainder of dividing x by y.  The
       return value is x-n*y, where n is the value x / y, rounded to the
       nearest integer.  If the absolute value of x-n*y is 0.5, n is
       chosen to be even.

       These functions are unaffected by the current rounding mode (see
       fenv(3)).

       The drem() function does precisely the same thing.

RETURN VALUE

       On success, these functions return the floating-point remainder,
       x-n*y.  If the return value is 0, it has the sign of x.

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

       If x is an infinity, and y is not a NaN, a domain error occurs,
       and a NaN is returned.

       If y is zero, and x is not a NaN, a domain error occurs, and a
       NaN is returned.

ERRORS

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

       The following errors can occur:

       Domain error: x is an infinity and y is not a NaN
              errno is set to EDOM (but see BUGS).  An invalid floating-
              point exception (FE_INVALID) is raised.

              These functions do not set errno for this case.

       Domain error: y is zero
              errno is set to EDOM.  An invalid floating-point exception
              (FE_INVALID) is raised.

ATTRIBUTES

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

STANDARDS

       remainder()
       remainderf()
       remainderl()
              C11, POSIX.1-2008.

       drem()
       dremf()
       dreml()
              None.

HISTORY

       remainder()
       remainderf()
       remainderl()
              C99, POSIX.1-2001.

       drem() 4.3BSD.

       dremf()
       dreml()
              Tru64, glibc2.

BUGS

       Before glibc 2.15, the call

           remainder(nan(""), 0);

       returned a NaN, as expected, but wrongly caused a domain error.
       Since glibc 2.15, a silent NaN (i.e., no domain error) is
       returned.

       Before glibc 2.15, errno was not set to EDOM for the domain error
       that occurs when x is an infinity and y is not a NaN.

EXAMPLES

       The call "remainder(29.0, 3.0)" returns -1.

SEE ALSO

       div(3), fmod(3), remquo(3)

COLOPHON

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Linux man-pages 6.9.1          2024-05-02                   remainder(3)

Pages that refer to this page: div(3), fma(3), fmod(3), remquo(3)

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