HP-UX Reference (11i v3 07/02) - 3 Library Functions A-M (vol 6)

ManualsBrandsHP ManualsSoftwareHP-UX Reference Manuals

431

432

433

434

435

436

437

438

439

440

fesetround(3M) fesetround(3M)

NAME

fesetround() - set ﬂoating-point rounding direction mode

SYNOPSIS

#include <fenv.h>

int fesetround(int round);

DESCRIPTION

The fesetround() function establishes the rounding direction represented by its argument round. The

round argument must equal one of the macros:

FE_TONEAREST , FE_UPWARD, FE_DOWNWARD , and

FE_TOWARDZERO

. If the argument does not match a rounding direction macro, the rounding direction is

not changed.

The default rounding direction mode is round to nearest (

FE_TONEAREST ).

USAGE

To use this function, compile either with the default

-Ae option or with the -Aa and -D_HPUX_SOURCE

options. Make sure your program includes <fenv.h>

For HP Integrity servers, specify

+Ofenvaccess on the compiler command line or place the call to this

function under the effect of an afﬁrmative FENV_ACCESS pragma:

#pragma STDC FENV_ACCESS ON

If the FENV_ACCESS pragma is placed outside of any top-level declarations in a ﬁle, the pragma will

apply to all declarations in the compilation following the pragma until another FENV_ACCESS pragma is

encountered or until the end of the ﬁle is reached.

If the FENV_ACCESS pragma is placed at the beginning of a block (compound statement), the pragma will

apply until another FENV_ACCESS pragma is encountered or until the end of the block is reached.

For PA-RISC, you might need to use the

+Onomoveflops compiler option in order to prevent optimiza-

tions that can undermine the speciﬁed behavior of this function.

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

RETURN VALUE

The

fesetround() function returns a zero value if and only if the argument is equal to a rounding

direction macro.

ERRORS

No errors are deﬁned.

EXAMPLES

Save, set, and restore the rounding direction.

#include <fenv.h>

/*...*/

{

int save_round;

save_round = fegetround();

fesetround(FE_UPWARD);

/*...*/

fesetround(save_round);

/*...*/

}