+ /* Positive numbers. */
+ ASSERT (!signbit (roundl (0.3L)));
+ ASSERT (!signbit (roundl (0.7L)));
+ /* Negative numbers. */
+ ASSERT (!!signbit (roundl (-0.3L)) == !!signbit (minus_zerol));
+ ASSERT (!!signbit (roundl (-0.7L)) == !!signbit (minus_zerol));