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HP-UX 11i Version 3: February 2007

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round(), roundf(), roundl(), roundw(), roundq() — round functions


#include <math.h>

double round(double x);

HP Integrity Server Only

float roundf(float x);

long double roundl(long double x);

extended roundw(extended x);

quad roundq(quad x);


The round() function rounds its argument to the nearest integral value in floating-point format. An argument exactly halfway between two integers is rounded away from zero, regardless of the current rounding direction. Rounding away from zero also applies to the functions, lround and llround.

Integrity Server Only

roundf() is a float version of round(); it takes a float argument and returns a float result.

roundl() is a long double version of round(); it takes a long double argument and returns a long double result.

roundw() is an extended version of round(); it takes an extended argument and returns an extended result.

roundq() is equivalent to roundl() on HP-UX systems.


To use these functions, compile either with the default -Ae option or with the -Aa and -D_HPUX_SOURCE options.

To use (for Integrity servers) roundw() or roundq(), compile also with the -fpwidetypes option.

To use these functions, make sure your program includes <math.h>. Link in the math library by specifying -lm on the compiler or linker command line.

For more information, see the HP-UX floating-point guide for HP Integrity servers at the following site: http://www.hp.com/go/fp.


If x is ±INFINITY or ±zero, round() returns x.

If x is NaN, round() returns NaN.

round() may raise the inexact exception if x is non integral and finite.


No errors are defined.


round(), roundf(), roundl() : ISO/IEC C99 (including Annex F, ``IEC 60559 floating-point arithmetic'')

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