fenv

bitwise OR of all supported floating-point exceptions

pole error occurred in an earlier floating-point operation

rounding towards negative infinity

inexact result: rounding was necessary to store the result of an earlier floating-point operation

domain error occurred in an earlier floating-point operation

the result of an earlier floating-point operation was too large to be representable

rounding towards nearest representable value

rounding towards zero

the result of an earlier floating-point operation was subnormal with a loss of precision

rounding towards positive infinity

Attempts to clear the floating-point exceptions that are listed in the bitmask argument excepts, which is a bitwise OR of the floating-point exception macros.

1. Attempts to store the status of the floating-point environment in the object pointed to by envp.

Attempts to obtain the full contents of the floating-point exception flags that are listed in the bitmask argument excepts, which is a bitwise OR of the floating-point exception macros.

Returns the value of the floating-point rounding macro that corresponds to the current rounding direction.

First, saves the current floating-point environment to the object pointed to by envp (similar to fegetenv), then clears all floating-point status flags, and then installs the non-stop mode: future floating-point exceptions will not interrupt execution (will not trap), until the floating-point environment is restored by feupdateenv or fesetenv.

This function may be used in the beginning of a subroutine that must hide the floating-point exceptions it may raise from the caller. If only some exceptions must be suppressed, while others must be reported, the non-stop mode is usually ended with a call to feupdateenv after clearing the unwanted exceptions.

Attempts to raise all floating-point exceptions listed in excepts (a bitwise OR of the floating-point exception macros). If one of the exceptions is FE_OVERFLOW or FE_UNDERFLOW, this function may additionally raise FE_INEXACT. The order in which the exceptions are raised is unspecified, except that FE_OVERFLOW and FE_UNDERFLOW are always raised before FE_INEXACT.

2. Attempts to establish the floating-point environment from the object pointed to by envp. The value of that object must be previously obtained by a call to feholdexcept or fegetenv or be a floating-point macro constant. If any of the floating-point status flags are set in envp, they become set in the environment (and are then testable with fetestexcept), but the corresponding floating-point exceptions are not raised (execution continues uninterrupted)

Attempts to copy the full contents of the floating-point exception flags that are listed in excepts from flagp into the floating-point environment. Does not raise any exceptions, only modifies the flags.

Attempts to establish the floating-point rounding direction equal to the argument round, which is expected to be one of the floating-point rounding macros.

Determines which of the specified subset of the floating-point exceptions are currently set. The argument excepts is a bitwise OR of the floating-point exception macros.

First, remembers the currently raised floating-point exceptions, then restores the floating-point environment from the object pointed to by envp (similar to fesetenv), then raises the floating-point exceptions that were saved.

This function may be used to end the non-stop mode established by an earlier call to feholdexcept.