The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008, 2016 Edition
Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

> remquo, remquof, remquol - remainder functions

#### SYNOPSIS

> ``#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

> [CX] 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

> 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.

> [MX] 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

> These functions shall fail if:

> Domain Error
>   [MX] 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

> 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

> 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

> None.

#### SEE ALSO

> feclearexcept, fetestexcept, remainder

> XBD Treatment of Error Conditions for Mathematical Functions, <math.h>

#### CHANGE HISTORY

> First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.

#### Issue 7

> ISO/IEC 9899:1999 standard, Technical Corrigendum 2 #56 (SD5-XSH-ERN-83) is applied.

> POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0507 [320] is applied.

End of informative text.

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