Floating point environment

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Revision as of 22:37, 31 May 2013 by P12bot (Talk | contribs)

The floating-point environment is the set of floating-point status flags and control modes supported by the implementation. It is thread-local, each thread inherits the initial state of its floating-point environment from the parent thread. Floating-point operations modify the floating-point status flags to indicate abnormal results or auxiliary information. The state of floating-point control modes affects the outcomes of some floating-point operations.

The floating-point environment access and modification is only meaningful when #pragma STDC FENV_ACCESS is set to ON. Otherwise the implementation is free to assume that floating-point control modes are always the default ones and that floating-point status flags are never tested or modified. In practice, few current compilers support the #pragma explicitly, but most compilers allow meaningful access to the floating-point environment anyway.


Defined in header <fenv.h>
fenv_t The type representing the entire floating-point environment
fexcept_t The type representing all floating-point status flags collectively


clears the specified floating-point status flags
(function) [edit]
determines which of the specified floating-point status flags are set
(function) [edit]
raises the specified floating-point exceptions
(function) [edit]
copies the state of the specified floating-point status flags from or to the floating-point environment
(function) [edit]
gets or sets rounding direction
(function) [edit]
saves or restores the current floating point environment
(function) [edit]
saves the environment, clears all status flags and ignores all future errors
(function) [edit]
restores the floating-point environment and raises the previously raise exceptions
(function) [edit]


floating-point exceptions
(macro constant) [edit]
floating-point rounding direction
(macro constant) [edit]
default floating-point environment
(macro constant) [edit]