FMOD(P) POSIX Programmer s Manual FMOD(P)

PROLOG This manual page is part of the POSIX Programmer s Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

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 divi- sion 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 imple- mentation-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 sup- ported), or an implementation-defined value shall be returned.

If x is infinite, a domain error shall occur, and either a NaN (if sup- ported), 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 vol- ume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Condi- tions 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 .

IEEE/The Open Group 2003 FMOD(P)