개요

• 솔라나라에 설명된 어플리케이션에 대해 맨 페이지를 찾아 출력한다.
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feupdateenv(3m)

Mathematical Library Functions                                 feupdateenv(3M)



NAME
       feupdateenv - update floating-point environment

SYNOPSIS
       c99 [ flag... ] file... -lm [ library... ]
       #include <fenv.h>

       int feupdateenv(const fenv_t *envp);

DESCRIPTION
       The feupdateenv() function attempts to save the currently raised float‐
       ing-point exceptions in its automatic storage, attempts to install  the
       floating-point  environment  represented  by  the  object pointed to by
       envp, and then attempts to raise the saved  floating-point  exceptions.
       The  envp argument points to an object set by a call to fegetenv(3M) or
       feholdexcept(3M), or equals a floating-point environment macro.

RETURN VALUES
       The feupdateenv() function returns 0 if and only if  all  the  required
       actions were successfully carried out.

ERRORS
       No errors are defined.

EXAMPLES
       The  following example demonstrates sample code to hide spurious under‐
       flow floating-point exceptions:

       Example 1 Hide spurious underflow floating-point exceptions.


         #include <fenv.h>
         double f(double x)
         {
         #   pragma STDC FENV_ACCESS ON
             double result;
             fenv_t save_env;
             feholdexcept(&save_env);
             // compute result
             if (/* test spurious underflow */)
             feclearexcept(FE_UNDERFLOW);
             feupdateenv(&save_env);
             return result;
         }



ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i)


       ATTRIBUTE TYPEATTRIBUTE VALUE _ Interface StabilityCommitted  _  Avail‐
       abilitysystem/library/math   _   MT-LevelMT-Safe  _  StandardSee  stan‐
       dards(7).


SEE ALSO
       fenv.h(3HEAD),  fegetenv(3M),  feholdexcept(3M),  attributes(7),  stan‐
       dards(7)

NOTES
       In  a  multithreaded  program,  the  feupdateenv() function affects the
       floating point environment only for the calling thread.


       When the FEX_CUSTOM handling mode is in effect for an exception,  rais‐
       ing  that exception using feupdateenv() causes the handling function to
       be invoked. The handling function can then modify the  exception  flags
       to  be  set  as described in fex_set_handling(3M). Any result value the
       handler supplies will be ignored.


       The feupdateenv() function automatically installs and deinstalls SIGFPE
       handlers  and sets and clears the trap enable mode bits in the floating
       point status register as needed. If a program uses these functions  and
       attempts  to  install  a SIGFPE handler or control the trap enable mode
       bits independently, the resulting behavior is not defined.


       As  described  in  fex_set_handling(3M),  when  a   handling   function
       installed  in  FEX_CUSTOM mode is invoked, all exception traps are dis‐
       abled (and will not  be  reenabled  while  SIGFPE  is  blocked).  Thus,
       attempting  to  change the environment from within a handler by calling
       fesetenv(3M) or feupdateenv() might not produce the expected results.



Solaris 11.4                     27 Sept 2016                  feupdateenv(3M)