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REMAINDER(3) Linux Programmer's Manual REMAINDER(3)

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

#include <math.h>
/* The C99 versions */
double remainder(double x, double y);
float remainderf(float x, float y);
long double remainderl(long double x, long double y);
/* Obsolete synonyms */
double drem(double x, double y);
float dremf(float x, float y);
long double dreml(long double x, long double y);


Link with -lm.




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 versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE



remainderf(), remainderl():

_ISOC99_SOURCE ||
  _POSIX_C_SOURCE >= 200112L


 || /* Since glibc 2.19: */ _DEFAULT_SOURCE


 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE



drem(), dremf(), dreml():

/* Since glibc 2.19: */ _DEFAULT_SOURCE


 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE








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.








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.








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 EDOM (but see BUGS). An invalid
      floating-point exception (FE_INVALID) is raised.





  

  
These functions do not set errno for this case.





  

  
errno is set to EDOM. An invalid floating-point exception
      (FE_INVALID) is raised.










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



  

    Interface
    Attribute
    Value
  

  

    drem (), dremf (), dreml (), remainder (), remainderf (), remainderl
      ()
    Thread safety
    MT-Safe
  










The functions remainder(), remainderf(), and
    remainderl() are specified in C99, POSIX.1-2001, and
  POSIX.1-2008.


The function drem() is from 4.3BSD. The float and
    long double variants dremf() and dreml() exist on some
    systems, such as Tru64 and glibc2. Avoid the use of these functions in favor
    of remainder() etc.








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.








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








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








This page is part of release 5.10 of the Linux man-pages
    project. A description of the project, information about reporting bugs, and
    the latest version of this page, can be found at
    https://www.kernel.org/doc/man-pages/.







  

    2020-06-09