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feholdexcept(3m) [opensolaris man page]

feholdexcept(3M)					  Mathematical Library Functions					  feholdexcept(3M)

NAME
feholdexcept - save current floating-point environment SYNOPSIS
c99 [ flag... ] file... -lm [ library... ] #include <fenv.h> int feholdexcept(fenv_t *envp); DESCRIPTION
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 (continue on floating-point exceptions) mode, if available, for all floating-point exceptions. RETURN VALUES
The feholdexcept() function returns 0 if and only if non-stop floating-point exception handling was successfully installed. ERRORS
No errors are defined. 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), fenv.h(3HEAD), feupdateenv(3M), attributes(5), standards(5) NOTES
In a multithreaded program, the feholdexcept() function affects the floating point environment only for the calling thread. The feholdexcept() 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. SunOS 5.11 12 Jul 2006 feholdexcept(3M)

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feupdateenv(3M) 					  Mathematical Library Functions					   feupdateenv(3M)

NAME
feupdateenv - update floating-point environment SYNOPSIS
cc [ 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 5.10 1 Sep 2002 feupdateenv(3M)
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