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Home > Floating-point support > Double precision data type for IEEE 754 arithmetic |

A double value is 64 bits wide. Figure 2 shows its structure.

As before, `S`

is the sign, `Exp`

the
exponent, and `Frac`

the fraction. Most of the
detail of float values remains true for double values,
except that:

The

`Exp`

field is biased by`0x3FF`

(1023) instead of`0x7F`

, so numbers between 1.0 and 2.0 have an`Exp`

field of`0x3FF`

.The

`Exp`

value used to represent infinity and NaNs is`0x7FF`

(2047) instead of`0xFF`

.

- Concepts
- Reference
- Other information
*IEEE Standard for Floating-Point Arithmetic*(IEEE 754), 1985 version