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Using the GNU Compiler Collection (GCC)

4.6 Floating point

• The accuracy of the floating-point operations and of the library functions in <math.h> and <complex.h> that return floating-point results (5.2.4.2.2).

• The rounding behaviors characterized by non-standard values of FLT_ROUNDS (5.2.4.2.2).

• The evaluation methods characterized by non-standard negative values of FLT_EVAL_METHOD (5.2.4.2.2).

• The direction of rounding when an integer is converted to a floating-point number that cannot exactly represent the original value (6.3.1.4).

• The direction of rounding when a floating-point number is converted to a narrower floating-point number (6.3.1.5).

• How the nearest representable value or the larger or smaller representable value immediately adjacent to the nearest representable value is chosen for certain floating constants (6.4.4.2).

• Whether and how floating expressions are contracted when not disallowed by the FP_CONTRACT pragma (6.5).

• The default state for the FENV_ACCESS pragma (7.6.1).

• Additional floating-point exceptions, rounding modes, environments, and classifications, and their macro names (7.6, 7.12).

• The default state for the FP_CONTRACT pragma (7.12.2).

• Whether the "inexact" floating-point exception can be raised when the rounded result actually does equal the mathematical result in an IEC 60559 conformant implementation (F.9).

• Whether the "underflow" (and "inexact") floating-point exception can be raised when a result is tiny but not inexact in an IEC 60559 conformant implementation (F.9).