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FECLEAREXCEPT(3)      DragonFly Library Functions Manual      FECLEAREXCEPT(3)

NAME
     feclearexcept, fegetexceptflag, feraiseexcept, fesetexceptflag,
     fetestexcept -- access floating-point status flags

SYNOPSIS
     #include <fenv.h>

     int
     feclearexcept(int excepts);

     int
     fegetexceptflag(fexcept_t *flagp, int excepts);

     int
     feraiseexcept(int excepts);

     int
     fesetexceptflag(const fexcept_t *flagp, int excepts);

     int
     fetestexcept(int excepts);

DESCRIPTION
     These functions provide access to the floating-point status flags.  The
     excepts input argument is a bitmask specifying an exception type and
     containing any of the values listed below.

     FE_DIVBYZERO  A divide-by-zero exception occurs when the program attempts
                   to divide a finite non-zero number by zero.

     FE_INEXACT    An inexact exception is raised whenever there is a loss of
                   precision due to rounding.

     FE_INVALID    Invalid operation exceptions occur when a program attempts
                   to perform calculations for which there is no reasonable
                   representable answer.

                   For instance, subtraction of infinities, division of zero
                   by zero, ordered comparison involving NaNs, and taking the
                   square root of a negative number are all invalid
                   operations.

     FE_OVERFLOW   An overflow exception occurs when the magnitude of the
                   result of a computation is too large to fit in the
                   destination type.

     FE_UNDERFLOW  Underflow occurs when the result of a computation is too
                   close to zero to be represented as a non-zero value in the
                   destination type.

     FE_DENORMAL   Denormalization exception occurs when the result of a
                   floating-point expression is a denormalized number.

                   This is available only on the floating-point
                   implementations of amd64 and i386 processors.

     Additionally, the macro FE_ALL_EXCEPT is simply the bitwise OR of all
     floating-point exception macros listed above.

     The feclearexcept() function clears the floating-point exceptions
     represented by excepts.

     The fegetexceptflag() function stores a representation of the states of
     the floating-point flags indicated by excepts in the object pointed to by
     flagp.

     The feraiseexcept() function raises floating-point exceptions represented
     by excepts.

     The fesetexceptflag() function sets the floating-point status flags
     indicated by excepts to the states stored in the object pointed to by
     flagp.  The value of flagp shall have been set by a previous call to
     fegetexceptflag() whose second argument represented at least those
     floating-point exceptions represented by excepts.  This function does not
     raise floating-point exceptions, but only sets the state of the flags.

     The fetesteexcept() function determines which of a specified subset of
     the floating-point exception flags are currently set.  The excepts
     specifies the floating-point status flags to be queried.

RETURN VALUES
     The feclearexcept(), fegetexceptflag(), feraiseexcept(), and
     fesetexceptflag() functions return zero on success, and non-zero if an
     error occurred.  The fetestexcept() function returns a bitmask of a
     specified subset of the floating-point exception flags which are
     currently set.

SEE ALSO
     feenableexcept(3), fegetenv(3), fegetround(3)

STANDARDS
     The feclearexcept(), fegetexceptflag(), feraiseexcept(),
     fesetexceptflag(), and fetestexcept() functions conform to ISO/IEC
     9899:1999 (``ISO C99'').

     The return types for feclearexcept(), fegetexceptflag(), feraiseexcept(),
     and fesetexceptflag() are int for alignment with ISO/IEC 9899:1999
     (``ISO C99'') Defect Report #202.

HISTORY
     These functions first appeared in OpenBSD 5.0.

CAVEATS
     On some architectures, feraiseexcept() additionally raises the
     ``inexact'' floating-point exception whenever it raises the ``overflow''
     or ``underflow'' floating-point exception.

DragonFly 4.1                    June 5, 2013                    DragonFly 4.1