rint(), rintf(), rintl()

Round to the nearest integral value

Synopsis:

#include <math.h>

double rint ( double x );

float rintf ( float x );

long double rintl( long double x );

Arguments:

x: The number that you want to round.

Library:

libm: The general-purpose math library.
libm-sve: (QNX Neutrino 7.1 or later) A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

If you want only selected processes to run with the SVE version, you can include both libraries in your OS image and use the -l m or -l m-sve option to qcc to link explicitly against the appropriate one.
If you want all processes to use the SVE version, include libm-sve.so in your OS image and set up a symbolic link from libm.so to libm-sve.so. Use the -l m option to qcc to link against the library.

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.

Description:

The rint(), rintf(), and rintl() functions return the integral value nearest x in the direction of the current rounding mode (see fesetround()).

If the current rounding mode rounds toward negative infinity, then rint() is identical to floor(). If the current rounding mode rounds toward positive infinity, then rint() is identical to ceil().

To check for error situations, use feclearexcept() and fetestexcept(). For example:

Call feclearexcept(FE_ALL_EXCEPT) before calling rint(), rintf(), or rintl().
On return, if fetestexcept(FE_ALL_EXCEPT) is nonzero, then an error has occurred.

Returns:

An integer (represented as a double precision number) nearest x in the direction of the current rounding mode. The result has the same sign as x.

If `x` is:	rint() returns:	Errors:
±Inf	`x`	—
NaN	`x`	—

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.

Examples:

#include <stdio.h>
#include <math.h>
#include <fenv.h>
#include <stdlib.h>

int main( void )
{
    int except_flags;
    double a, b;

    feclearexcept(FE_ALL_EXCEPT);
    a = 0.7 ;
    b = rint(a);

    except_flags = fetestexcept(FE_ALL_EXCEPT);
    if(except_flags) {
        /* An error occurred; handle it appropriately. */
    }

    printf("Round Native mode %f -> %f \n", a, b);

    return EXIT_SUCCESS;
}

Classification:

C11, POSIX 1003.1

Safety:
Cancellation point	No
Interrupt handler	Yes
Signal handler	Yes
Thread	Yes