The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.
A newer edition of this document exists here


remquo, remquof, remquol - remainder functions


#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);


[CX] [Option Start] 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 IEEE Std 1003.1-2001 defers to the ISO C standard. [Option End]

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.

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.


These functions shall return x REM y.

[MX] [Option Start] 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 either a NaN (if supported), or an implementation-defined value shall be returned. [Option End]


These functions shall fail if:

Domain Error
[MX] [Option Start] 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. [Option End]

The following sections are informative.




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.


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.




feclearexcept(), fetestexcept(), remainder(), the Base Definitions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Conditions for Mathematical Functions, <math.h>


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

End of informative text.

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