trusty (3) fmod.3posix.gz

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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>


       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 .