fpgetround(3C)       COMPATIBILITY FUNCTIONS       fpgetround(3C)



NAME
     fpgetround, fpsetround, fpgetmask,  fpsetmask,  fpgetsticky,
     fpsetsticky - IEEE floating-point environment control

SYNOPSIS
     #include <ieeefp.h>

     fp_rnd fpgetround (void);

     fp_rnd fpsetround (fp_rnd rnd_dir);

     fp_except fpgetmask (void);

     fp_except fpsetmask (fp_except mask);

     fp_except fpgetsticky (void);

     fp_except fpsetsticky (fp_except sticky);

DESCRIPTION
     There are five  floating-point  exceptions:  divide-by-zero,
     overflow, underflow, imprecise (inexact) result, and invalid
     operation.  When  a  floating-point  exception  occurs,  the
     corresponding  sticky bit is set (1), and if the mask bit is
     enabled (1), the trap takes place.  These routines  let  the
     user  change  the  behavior  on  occurrence  of any of these
     exceptions,  as  well  as  change  the  rounding  mode   for
     floating-point operations.

          FP_X_INV  /* invalid operation exception */
          FP_X_OFL  /* overflow exception */
          FP_X_UFL  /* underflow exception */
          FP_X_DZ        /* divide-by-zero exception */
          FP_X_IMP  /* imprecise (loss of precision) */
          FP_RN     /* round to nearest representative number */
          FP_RP     /* round to plus infinity */
          FP_RM     /* round to minus infinity */
          FP_RZ     /* round to zero (truncate) */

     fpgetround returns the current rounding mode.

     fpsetround sets the rounding mode and returns  the  previous
     rounding mode.

     fpgetmask returns the current exception masks.

     fpsetmask sets the exception masks and returns the  previous
     setting.

     fpgetsticky returns the current exception sticky flags.





          Last change: C Programming Language Utilities         1

fpgetround(3C)       COMPATIBILITY FUNCTIONS       fpgetround(3C)



     fpsetsticky sets (clears) the  exception  sticky  flags  and
     returns the previous setting.

     The default environment is  rounding  mode  set  to  nearest
     (FP_RN) and all traps disabled.

     Individual bits may be examined using the constants  defined
     in ieeefp.h.

SEE ALSO
     isnan(3C).

NOTES
     fpsetsticky modifies all sticky  flags.   fpsetmask  changes
     all  mask bits.  fpsetmask clears the sticky bit correspond-
     ing to any exception being enabled.

     C requires truncation (round to zero) for floating point  to
     integral  conversions.   The  current  rounding  mode has no
     effect on these conversions.  One must clear the sticky  bit
     to  recover from the trap and to proceed.  If the sticky bit
     is not cleared before the next trap occurs, a  wrong  excep-
     tion type may be signaled.
































          Last change: C Programming Language Utilities         2