'the most accurate approximation of pi in IEEE-754 float64?
what is the most accurate approximation of pi possible in IEEE-754 float64?
fwiw it seems both Javascript and PHP use 3.141592653589793115997963468544185161590576171875
, which might be the answer, i don't know.
Solution 1:[1]
Yes, 3.141592653589793115997963468544185161590576171875 is the IEEE-754 binary641 number closest to ?. It can also be written as a hexadecimal floating-point constant, 0x1.921fb54442d18p1. (I keep 0x3.243f6a8885a308d313198a2e03707344ap0L on hand to have the value for wider formats as well.) The C standard requires C implementations that use a base-two floating-point format to correctly round hexadecimal floating-point constants, and it does not require that for decimal floating-point constants, so you may be more likely to get a correct result when you use the hexadecimal form.
Footnote
1 IEEE-754 2008 uses “binary64” for the standard 64-bit base-two format. It is also called “double precision.” Some programming languages might call it float64 or Float64.
Sources
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Source: Stack Overflow
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