Difference between revisions of "c/numeric/fenv"

Revision as of 19:28, 2 November 2012

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.

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