NAME

       fmod, fmodf, fmodl - floating-point remainder value function

SYNOPSIS

       #include <math.h>

       double fmod(double x, double y);
       float fmodf(float x, float y);
       long double fmodl(long double x, long double y);

DESCRIPTION

       These functions shall return the floating-point remainder of the division of x by y.

       An  application  wishing  to  check for error situations should set errno to zero and call
       feclearexcept(FE_ALL_EXCEPT) before calling these functions.  On return, if errno is  non-
       zero  or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero,
       an error has occurred.

RETURN VALUE

       These functions shall return the value x- i* y, for some integer i such that, if y is non-
       zero, the result has the same sign as x and magnitude less than the magnitude of y.

       If  the  correct  value would cause underflow, and is not representable, a range error may
       occur, and    either 0.0 (if supported), or   an  implementation-defined  value  shall  be
       returned.

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

       If  y  is  zero,  a  domain  error  shall  occur,  and  either a NaN (if supported), or an
       implementation-defined value shall be returned.

       If x is infinite, a domain error shall occur, and either  a  NaN  (if  supported),  or  an
       implementation-defined value shall be returned.

       If x is ±0 and y is not zero, ±0 shall be returned.

       If x is not infinite and y is ±Inf, x shall be returned.

       If  the correct value would cause underflow, and is representable, a range error may occur
       and the correct value shall be returned.

ERRORS

       These functions shall fail if:

       Domain Error
              The x argument is infinite or y is zero.

       If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be
       set  to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero,
       then the invalid floating-point exception shall be raised.

       These functions may fail if:

       Range Error
              The result underflows.

       If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be
       set  to  [ERANGE].  If  the integer expression (math_errhandling & MATH_ERREXCEPT) is non-
       zero, then the underflow floating-point exception shall be raised.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       On  error,  the  expressions  (math_errhandling  &  MATH_ERRNO)  and  (math_errhandling  &
       MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       feclearexcept()   ,   fetestexcept()   ,   isnan()   ,  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001,  Section  4.18,  Treatment  of  Error  Conditions  for  Mathematical
       Functions, <math.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .