```REMQUO(3P)                POSIX Programmer's Manual               REMQUO(3P)
```

PROLOG         top

```       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         top

```       remquo, remquof, remquol — remainder functions
```

SYNOPSIS         top

```       #include <math.h>

double remquo(double x, double y, int *quo);
float remquof(float x, float y, int *quo);
long double remquol(long double x, long double y, int *quo);
```

DESCRIPTION         top

```       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.

The remquo(), remquof(), and remquol() functions shall compute the
same remainder as the remainder(), remainderf(), and remainderl()
functions, respectively. In the object pointed to by quo, they store
a value whose sign is the sign of x/y and whose magnitude is
congruent modulo 2n to the magnitude of the integral quotient of x/y,
where n is an implementation-defined integer greater than or equal to
3. If y is zero, the value stored in the object pointed to by quo is
unspecified.

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         top

```       These functions shall return x REM y.

On systems that do not support the IEC 60559 Floating-Point option,
if y is zero, it is implementation-defined whether a domain error
occurs or zero is returned.

If x or y is NaN, a NaN shall be returned.

If x is ±Inf or y is zero and the other argument is non-NaN, a domain
error shall occur, and a NaN shall be returned.
```

ERRORS         top

```       These functions shall fail if:

Domain Error
The x argument is ±Inf, or the y argument is ±0 and the
other argument is non-NaN.

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:

Domain Error
The y argument 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.

The following sections are informative.
```

EXAMPLES         top

```       None.
```

APPLICATION USAGE         top

```       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         top

```       These functions are intended for implementing argument reductions
which can exploit a few low-order bits of the quotient. Note that x
may be so large in magnitude relative to y that an exact
representation of the quotient is not practical.
```

FUTURE DIRECTIONS         top

```       None.
```

```       feclearexcept(3p), fetestexcept(3p), remainder(3p)

The Base Definitions volume of POSIX.1‐2008, Section 4.19, Treatment
of Error Conditions for Mathematical Functions, math.h(0p)
```

```       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.1-2008 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 .