About
Float64 is a floating point number with a 64bit precision.
Float64 is also known as:
- 64-bit floating-point values,
- double precision floating-point
- 64-bit IEEE-754 floating-point
- or just double
It is a number bit representation that permits to store/manipulate:
- or float point
in a computer
It's a logical data type. While your variable may have a float64 data type, the language engine will not store numbers in Float64 all the time because it will be terribly inefficient on a storage level.
Language
- C: double. (implemented as a 64-bit IEEE 754 number, which uses 52 bits of space for the mantissa)
- Java: double
Characteristic
Storage
Storing numbers in Float64 would be terribly inefficient
Example: The integer number 42 in bit representation
| representation | bit |
|---|---|
| Float 64 | 0100 0000 0100 0101 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 |
| Others | |
| two’s complement 8-bit | 0010 1010 |
| two’s complement 32-bit | 0000 0000 0000 0000 0000 0000 0010 1010 |
| packed binary-coded decimal (BCD) | 0100 0010 |
| 32-bit IEEE-754 floating-point | 0100 0010 0010 1000 0000 0000 0000 0000 |
Max / Min
- 53 bit is the maximum storage in Javascript
console.log(Number.MAX_SAFE_INTEGER); // 2^53 - 1
console.log(Number.MIN_SAFE_INTEGER); // (-(2^53 - 1)).