Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

feupdateenv(3m) [opensolaris man page]

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 floating-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 excep- tions. 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 underflow 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(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
fegetenv(3M), feholdexcept(3M), fenv.h(3HEAD), attributes(5), standards(5) 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, raising 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 disabled (and will not be reenabled while SIGFPE is blocked). Thus, attempting to change the environment from within a handler by calling fes- etenv(3M) or feupdateenv might not produce the expected results. SunOS 5.11 12 Jul 2006 feupdateenv(3M)

Check Out this Related Man Page

FEGETENV(3)						   BSD Library Functions Manual 					       FEGETENV(3)

NAME
fegetenv, feholdexcept, fesetenv, feupdateenv -- functions providing access to the floating-point environment. SYNOPSIS
#include <fenv.h> #pragma STDC FENV_ACCESS ON int fegetenv(fenv_t *envp); int feholdexcept(fenvt_t *envp); int fesetenv(fenv_t *envp); int feupdateenv(fenv_t *envp); DESCRIPTION
These functions provide the means to manage the entire floating-point environment--including both status flags and control modes--as a single entity. The fegetenv() function attempts to store the current floating-point environment in the object pointed to by envp. It returns zero if the environment was successfully stored, and a nonzero value otherwise. The feholdexcept() function saves the current floating-point environment in the object pointed to by envp, clears the floating-point status flags, and then installs a "non-stop" mode, if available, under which no traps are taken for floating-point exceptions (as is the case in default IEEE-754 floating-point execution). It returns zero if and only if such a mode was successfully installed. The fesetenv() function attempts to establish the floating-point environment represented by the object pointed to by envp. This object shall have been set by a call to fegetenv() or feholdexcept(), or be equal to a floating-point environment macro defined in <fenv.h>. Note that this function merely installs the floating-point status flags represented by its argument, and does not raise the corresponding floating- point exceptions. It returns zero if and only if the environment pointed to by envp was successfully installed. The feupdateenv() function attempts to save the currently raised floating-point flags, install the floating-point environment represented by *envp, and then raise the floating-point exceptions corresponding to the saved flags. The object pointed to by envp shall have been set by a call to fegetenv() or feholdexcept(), or be equal to a floating-point environment macro defined in <fenv.h>. It returns zero if and only if all of the specified actions were successfully carried out. SEE ALSO
fenv(3), feclearexcept(3), fegetexceptflag(3), fegetround(3), feraiseexcept(3), fesetexceptflag(3), fesetround(3), feraiseexcept(3) STANDARDS
These functions conform to ISO/IEC 9899:TC3. BSD
May 9, 2011 BSD
Man Page