nearbyint, nearbyintf, nearbyintl
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Defined in header
<math.h>
float nearbyintf( float arg );
(1)
(since C99)
double nearbyint( double arg );
(2)
(since C99)
long double nearbyintl( long double arg );
(3)
(since C99)
Defined in header
<tgmath.h>
#define nearbyint( arg )
(4)
(since C99)
1-3) Rounds the floating-point argument arg to an integer value in floating-point format, using the current rounding mode.
4) Type-generic macro: If arg has type long double,
nearbyintl is called. Otherwise, if arg has integer type or the type double, nearbyint is called. Otherwise, nearbyintf is called, respectively.[edit] Parameters
arg
-
floating-point value
[edit] Return value
The nearest integer value to arg, according to the current rounding mode, is returned.
[edit] Error handling
This function is not subject to any of the errors specified in math_errhandling.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
- FE_INEXACT is never raised.
- If arg is ±∞, it is returned, unmodified.
- If arg is ±0, it is returned, unmodified.
- If arg is NaN, NaN is returned.
[edit] Notes
The only difference between nearbyint and rint is that nearbyint never raises FE_INEXACT .
The largest representable floating-point values are exact integers in all standard floating-point formats, so nearbyint never overflows on its own; however the result may overflow any integer type (including intmax_t ), when stored in an integer variable.
If the current rounding mode is FE_TONEAREST , this function rounds to even in halfway cases (like rint , but unlike round ).
[edit] Example
Run this code
#include <fenv.h> #include <math.h> #include <stdio.h> int main(void) { // #pragma STDC FENV_ACCESS ON fesetround (FE_TONEAREST ); printf ("rounding to nearest:\nnearbyint(+2.3) = %+.1f ", nearbyint(2.3)); printf ("nearbyint(+2.5) = %+.1f ", nearbyint(2.5)); printf ("nearbyint(+3.5) = %+.1f\n", nearbyint(3.5)); printf ("nearbyint(-2.3) = %+.1f ", nearbyint(-2.3)); printf ("nearbyint(-2.5) = %+.1f ", nearbyint(-2.5)); printf ("nearbyint(-3.5) = %+.1f\n", nearbyint(-3.5)); fesetround (FE_DOWNWARD ); printf ("rounding down: \nnearbyint(+2.3) = %+.1f ", nearbyint(2.3)); printf ("nearbyint(+2.5) = %+.1f ", nearbyint(2.5)); printf ("nearbyint(+3.5) = %+.1f\n", nearbyint(3.5)); printf ("nearbyint(-2.3) = %+.1f ", nearbyint(-2.3)); printf ("nearbyint(-2.5) = %+.1f ", nearbyint(-2.5)); printf ("nearbyint(-3.5) = %+.1f\n", nearbyint(-3.5)); printf ("nearbyint(-0.0) = %+.1f\n", nearbyint(-0.0)); printf ("nearbyint(-Inf) = %+.1f\n", nearbyint(-INFINITY)); }
Output:
rounding to nearest: nearbyint(+2.3) = +2.0 nearbyint(+2.5) = +2.0 nearbyint(+3.5) = +4.0 nearbyint(-2.3) = -2.0 nearbyint(-2.5) = -2.0 nearbyint(-3.5) = -4.0 rounding down: nearbyint(+2.3) = +2.0 nearbyint(+2.5) = +2.0 nearbyint(+3.5) = +3.0 nearbyint(-2.3) = -3.0 nearbyint(-2.5) = -3.0 nearbyint(-3.5) = -4.0 nearbyint(-0.0) = -0.0 nearbyint(-Inf) = -inf
[edit] References
- C23 standard (ISO/IEC 9899:2024):
- 7.12.9.3 The nearbyint functions (p: TBD)
- 7.25 Type-generic math <tgmath.h> (p: TBD)
- F.10.6.3 The nearbyint functions (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.12.9.3 The nearbyint functions (p: TBD)
- 7.25 Type-generic math <tgmath.h> (p: TBD)
- F.10.6.3 The nearbyint functions (p: TBD)
- C11 standard (ISO/IEC 9899:2011):
- 7.12.9.3 The nearbyint functions (p: 251-252)
- 7.25 Type-generic math <tgmath.h> (p: 373-375)
- F.10.6.3 The nearbyint functions (p: 526)
- C99 standard (ISO/IEC 9899:1999):
- 7.12.9.3 The nearbyint functions (p: 232)
- 7.22 Type-generic math <tgmath.h> (p: 335-337)
- F.9.6.3 The nearbyint functions (p: 463)
[edit] See also
(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)
exception if the result differs
(function) [edit]
(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)
(function) [edit]
C++ documentation for nearbyint