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What is a 'precision'? what's the difference between single and double when using float and double? What do these lines mean - 'single-precision 32-bit IEEE 754 floating point' | 'double-precision 64-bit IEEE 754 floating point'

Ibteda Sabur
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  • ISTM that it can't be too hard to, say, google this. [Single precision](https://en.wikipedia.org/wiki/Single-precision_floating-point_format) is easy, so is [IEEE 754](https://en.wikipedia.org/wiki/IEEE_floating_point). – Rudy Velthuis Mar 23 '16 at 18:46

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"Single precision" and "double precision" refer to the number of machine words (4-byte/32 bit blocks) used to store a real number with varying degrees of accuracy.

IEEE 754 is just a standard -- by far the most dominant standard in modern computing -- for how you use those bits to represent a real number, by representing it as, essentially

 +/- 1.xyz... * 2^abc...

...where the question is how many bits of memory you use to store xyz and abc.

Louis Wasserman
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