fpgetround(3c)             DG/UX 4.30              fpgetround(3c)



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

     SYNOPSIS
          #include <ieeefp.h>

          fprnd fpgetround ();

          fprnd fpsetround (rnddir)
          fprnd rnddir;

          fpexcept fpgetmask ();

          fpexcept fpsetmask (mask)
          fpexcept mask;

          fpexcept fpgetsticky ();

          fpexcept fpsetsticky (sticky)
          fpexcept sticky;

     DESCRIPTION
          There are five floating-point exceptions:  divide-by-zero,
          overflow, underflow, imprecise (inexact) result, and invalid
          operation.  When a floating-point exception is detected, a
          trap (SIGFPE) occurs only when the corresponding mask bit is
          enabled.  Otherwise, the corresponding sticky bit is set and
          the standard IEEE-specified fixup is performed on the
          result.  These routines let the user control the behavior on
          occurrence of any of these exceptions, as well as the
          rounding mode for floating-point operations.

          Fpgetround returns the current rounding mode.  Fpsetround
          sets the rounding mode and returns the previous rounding
          mode.  The enumeration type fprnd (defined in <ieeefp.h>)
          comprises the following rounding modes:

          FP_RN        /* round to nearest */

          FP_RP        /* round to plus */

          FP_RM        /* round to minus */

          FP_RZ        /* round to zero (truncate) */

          Fpgetmask returns the current exception masks.

          Fpsetmask sets the exception masks and returns the previous
          setting.

          Fpgetsticky returns the current exception sticky flags.



     Licensed material--property of copyright holder(s)         Page 1

     fpgetround(3c)             DG/UX 4.30              fpgetround(3c)



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

          The type fpexcept is defined in <ieeefp.h>, along with the
          following exception masks:

          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) */

          The following defaults are in effect unless your program
          includes the file <ieeefp.h>:

               Rounding mode set to nearest (FP_RN).
               Divide-by-zero,
               floating-point overflow, and
               invalid operation traps enabled.

          If your program includes the file <ieeefp.h>, all traps are
          disabled.

     SEE ALSO
          isnan(3C).

     WARNINGS
          Fpsetsticky modifies all sticky flags.  Fpsetmask changes
          all mask bits.

          Both C and F77 require truncation (round to zero) for
          floating-point to integral conversions.  The rounding mode
          has no effect on these conversions.

          The sticky bit is never set when the trap for the exception
          is enabled.  As a result, it is currently impossible to
          determine what IEEE floating-point exception occurred from a
          C-coded signal handler.













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