математические декларации (mathematical declarations)
Использование в приложениях (Application usage)
The FP_CONTRACT pragma can be used to allow (if the state is on)
or disallow (if the state is off) the implementation to contract
expressions. Each pragma can occur either outside external
declarations or preceding all explicit declarations and
statements inside a compound statement. When outside external
declarations, the pragma takes effect from its occurrence until
another FP_CONTRACT pragma is encountered, or until the end of
the translation unit. When inside a compound statement, the
pragma takes effect from its occurrence until another FP_CONTRACT
pragma is encountered (including within a nested compound
statement), or until the end of the compound statement; at the
end of a compound statement the state for the pragma is restored
to its condition just before the compound statement. If this
pragma is used in any other context, the behavior is undefined.
The default state (on or off) for the pragma is implementation-
defined.
Applications should use FLT_MAX as described in the <float.h>
header instead of the obsolescent MAXFLOAT.
Note that if FLT_EVAL_METHOD is neither 0 nor 1, then some
constants might not compare equal as expected; for example,
(double)M_PI == M_PI can fail.
