remainder man page
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.
remainder, remainderf, remainderl — remainder function
Synopsis
#include <math.h> double remainder(double x, double y); float remainderf(float x, float y); long double remainderl(long double x, long double y);
Description
The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2008 defers to the ISO C standard.
These functions shall return the floatingpoint remainder r=xny when y is nonzero. The value n is the integral value nearest the exact value x/y. When nx/y=½, the value n is chosen to be even.
The behavior of remainder() shall be independent of the rounding mode.
Return Value
Upon successful completion, these functions shall return the floatingpoint remainder r=xny when y is nonzero.
On systems that do not support the IEC 60559 FloatingPoint option, if y is zero, it is implementationdefined whether a domain error occurs or zero is returned.
If x or y is NaN, a NaN shall be returned.
If x is infinite or y is 0 and the other is nonNaN, a domain error shall occur, and a NaN shall be returned.
Errors
These functions shall fail if:
 Domain Error

The x argument is ±Inf, or the y argument is ±0 and the other argument is nonNaN.
If the integer expression (math_errhandling & MATH_ERRNO) is nonzero, then errno shall be set to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is nonzero, then the invalid floatingpoint exception shall be raised.
These functions may fail if:
 Domain Error

The y argument is zero.
If the integer expression (math_errhandling & MATH_ERRNO) is nonzero, then errno shall be set to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is nonzero, then the invalid floatingpoint 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 nonzero.
Rationale
None.
Future Directions
None.
See Also
abs(), div(), feclearexcept(), fetestexcept(), ldiv()
The Base Definitions volume of POSIX.1‐2008, Section 4.19, 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, 2013 Edition, Standard for Information Technology  Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. (This is POSIX.12008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .
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