F.2 Types

• F.2.1 Infinities, signed zeros, and NaNs

1

The C floating types match the IEC 60559 formats as follows:

• The float type matches the IEC 60559 single format.

• The double type matches the IEC 60559 double format.

• The long double type matches an IEC 60559 extended format,[1] else a non-IEC 60559 extended format, else the IEC 60559 double format.

Any non-IEC 60559 extended format used for the long double type shall have more precision than IEC 60559 double and at least the range of IEC 60559 double.[2]

Recommended practice

2

The long double type should match an IEC 60559 extended format.

Footnotes

[1]

“Extended” is IEC 60559’s double-extended data format. Extended refers to both the common 80-bit and quadruple 128-bit IEC 60559 formats.

[2]

A non-IEC 60559 long double type is required to provide infinity and NaNs, as its values include all double values.