fmod
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);
Status
Partially implemented
Conformance
IEEE Std 1003.1-2017
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
fmod()
,modf()
, andfmodl()
shall return0.0
, or (if theIEC 60559
Floating-Point option is not supported) an implementation-defined value no greater in magnitude thanDBL_MIN
,FLT_MIN
, andLDBL_MIN
, respectively. -
If x or y is
NaN
, aNaN
shall be returned, and none of the conditions below shall be considered. - If y is zero, a domain error shall occur, and a
NaN
shall be returned. - If x is infinite, a domain error shall occur, and a
NaN
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, thenerrno
shall be set toEDOM
. - 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, thenerrno
shall be set toERANGE
. - If the integer expression
(math_errhandling & MATH_ERREXCEPT)
is non-zero, then the underflow floating-point exception shall be raised.
Tests
Untested
Known bugs
None