fmod(3p)
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 .