Double-precision floating-point format

Double-precision floating-point format (sometimes called FP64 or float64) is a <a href="/facts/Floating-point_arithmetic/eIckahxe">floating-point</a> <a href="/facts/Computer_number_format/fmLUI4hh">number format</a>, usually occupying 64 <a href="/facts/Bit/S972NSaD">bits</a> in computer memory; it represents a wide range of numeric values by using a floating <a href="/facts/Radix_point/3axE09oT">radix point</a>.
Double precision may be chosen when the range or precision of <a href="/facts/Single-precision_floating-point_format/e6Fez7BM">single precision</a> would be insufficient.
In the <a href="/facts/IEEE_754/dD3e7zAl">IEEE 754</a> <a href="/facts/Standardization/vS9AhNMS">standard</a>, the 64-bit base-2 format is officially referred to as binary64; it was called double in <a href="/facts/IEEE_754-1985/5uWBQrc0">IEEE 754-1985</a>. IEEE 754 specifies additional floating-point formats, including 32-bit base-2 single precision and, more recently, base-10 representations (<a href="/facts/Decimal_floating_point/1F9rG2Sn">decimal floating point</a>).
One of the first <a href="/facts/Programming_language/cWTYbgWa">programming languages</a> to provide floating-point data types was <a href="/facts/Fortran/m1KqjcMU">Fortran</a>. Before the widespread adoption of IEEE 754-1985, the representation and properties of floating-point data types depended on the <a href="/facts/Computer_manufacturer/PIU2T66l">computer manufacturer</a> and computer model, and upon decisions made by programming-language implementers. E.g., <a href="/facts/GW-BASIC/3XcQtD2e">GW-BASIC</a>'s double-precision data type was the <a href="/facts/64-bit_MBF/X1JpugSx">64-bit MBF</a> floating-point format.

Double-precision floating-point format open-in-new

Double-precision floating-point format